# Depth of Field (Bokeh) lesson



## minicoop1985 (Nov 14, 2016)

I took this shot today as a bit of a lesson for anyone interested. This is called depth of field, the field being the in focus area. The shallower the depth of field, the smaller the area in focus is. What controls the size of that field is your aperture. The lower the number for your aperture, the larger the diameter, so basically the opening of a 1.4 lens at 1.4 is much wider than one shot at 5.6. Now here's the fun part. MATH! The longer MM a lens is, for a given distance at same aperture, the DOF for the longer lens will be thinner. Also, sensor size plays into this as well-the larger the sensor, the longer the lenses needed to effectively cover the sensor area, so the larger the sensor, effectively, the thinner the DOF. This was shot on a Hasselblad H3D 39 medium format (aka a sensor 2X+ the size of the one in a full frame Canon or Nikon) with a 150mm f3.2 lens, shot wide open. No, I didn't blur it in post.




Fun with DOF! by Michael Long, on Flickr


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## Ysarex (Nov 14, 2016)

5.2mm lens (only 3.5% of 150mm) and shot on a sensor less than half the size of a postage stamp. I did leave the lens wide open at f/1.4 (cause I could).

Joe


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## KmH (Nov 15, 2016)

While depth-of-field (DoF) is adjustable, bokeh is fixed and not adjustable.

The aesthetic quality of the blurred foreground/background, bokeh, varies with each lens make/model.
Lens construction, the quality of the glass elements used in the lens, the lens element coatings, the number of aperture blades and the shape of the aperture blades all influence the visual aesthetic quality of the blurred regions created by controlling the DoF.


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## minicoop1985 (Nov 15, 2016)

Yeah, I meant bokeh separately from DOF. But that is a good point to bring up.


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## Bebulamar (Nov 16, 2016)

Didn't see any bokeh in either posted images. Lack of Depth of Field isn't a good thing.


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## Ysarex (Nov 16, 2016)

Bebulamar said:


> Didn't see any bokeh in either posted images. Lack of Depth of Field isn't a good thing.



Bokeh is apparent in both images. And both photos exhibit depth of field. How can a photograph lack depth of field?

Joe


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## Tim Tucker (Nov 17, 2016)

I would have to disagree with a number of points here.

The first is that aperture controls dof. It doesn't, it controls exposure. A lot of the nonsense I read is based on the assumption that aperture controls dof, but really all aperture does, and is calibrated for, is the accurate control of light intensity hitting the sensitive recording media.

There are four variables that affect dof; distance to subject, aperture, focal length, and image magnification. Focal length is irrespective of sensor size as the only variable here is image magnification for final viewing. A 150mm lens has the same dof on any sensor before you magnify the image, one of the main problems with larger formats is that you have to work with the inherently shorter dof of the longer "standard" lenses.

Shoot the stars with a 35mm at f1.4 and how much is in focus? Thats right, from about a few hundred yards to billions of miles away. Quite a dof. So is it really aperture or subject distance?

I do not dispute that aperture affects it, but it does not control it, it controls exposure.

Bokeh, or the character if the OOF is not set by the lens design alone but by lens design and aperture. The way a lens corrects, or under-corrects, aberrations and the way it blends the various corrections of many aberrations is what creates the "character" of the bokeh. And the aberrations are directly affected by aperture.


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## Ysarex (Nov 17, 2016)

Tim Tucker said:


> There are four variables that affect dof; distance to subject, aperture, focal length, and image magnification.



Don't forget the size of the recording media. All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size.

Joe


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## Tim Tucker (Nov 17, 2016)

Ysarex said:


> Tim Tucker said:
> 
> 
> > There are four variables that affect dof; distance to subject, aperture, focal length, and image magnification.
> ...



Not really. The difference in dof is due to the magnification of the image to the final viewed size. With all being equal then a 150mm lens will produce the same circles of confusion regardless of the sensor size, it's just how much you magnify it in the finished image, (and how that relates to viewing distance).


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## Ysarex (Nov 17, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > Tim Tucker said:
> ...



Not really, to take the *same photo* with two different cameras using different size recording media the camera with the smaller sensor/film will produce deeper DOF all other factors adjusted so as to produce the *same photo. No comparison is otherwise appropriate* except one in which you use the two cameras to take the *same photo*. 

To take the same photo both cameras must be in the same place. The field of view at least against the long side of the media (assuming possible different aspect ratios) must be the same and the exposure must be the same.

Joe


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## freddy21 (Nov 17, 2016)

I use an Android app on the go simply named DoF.  Its an excellent calculator to have with you and at hand.  Especially if you let the DOF get too shallow like I do with my 50mm f1.8 all the time.


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## Tim Tucker (Nov 18, 2016)

Ysarex said:


> Not really, to take the *same photo* with two different cameras using different size recording media the camera with the smaller sensor/film will produce deeper DOF all other factors adjusted so as to produce the *same photo. No comparison is otherwise appropriate* except one in which you use the two cameras to take the *same photo*.
> 
> To take the same photo both cameras must be in the same place. The field of view at least against the long side of the media (assuming possible different aspect ratios) must be the same and the exposure must be the same.
> 
> ...



I really do not hold with this "equivalence", or same photo nonsense, (in fact it annoys me ), because it's so meaningless and misleading.

If in your instance you hold _exposure_ (or same f-stop) as constant and to satisfy the condition of *the same photo* you also have changed the focal length and the amount you magnify the finished image to the final print. The sensor size does not change the way the light passes through the lens, it's only affect on dof is the amount you have to magnify it to produce the final image.

Take for example the following case which is encountered in normal photography:

You take a photo with a camera and a certain lens, you print it 10"x8". You then crop it, (after the brilliant advice you receive off this site), and print again at 10"x8". How does that affect the dof? Are you going to tell me that the case is irrelevant because it does not satisfy the condition of *the same photo*? Of course not. 

The whole system of exposure/fov/dof is very symmetrical and if you hold some things constant then others cancel out. In equivalence where you take the same photo (and same dof) with a different sensor is a very special case where a number of variables *must* be held constant. In this special case a number of other variables cancel out.

To explain, in order to satisfy the condition of *the same photo* (with the same dof) then subject distance, fov and _aperture diameter in mm_ *must* be held constant. In this instance _exposure_ *must* vary but focal length cancels out of the equation. But we do not take photos like this.

In your case you substitute _exposure_ for _aperture diameter in mm_ but still insist that other things must be held constant such as fov and subject distance and the conclusion is that sensor size affects dof, which it does not directly do. A fuller understanding is that with smaller sensors you use shorter focal length lenses and to maintain exposure you are using a smaller _aperture diameter in mm_ which results in the increased dof, it happens before it reaches the sensor and happens when you use shorter focal length lenses on the same sensor.


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## Braineack (Nov 18, 2016)




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## Ysarex (Nov 18, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > Not really, to take the *same photo* with two different cameras using different size recording media the camera with the smaller sensor/film will produce deeper DOF all other factors adjusted so as to produce the *same photo. No comparison is otherwise appropriate* except one in which you use the two cameras to take the *same photo*.
> ...



Yeah, it annoys me too. But you can't use that as an excuse.



Tim Tucker said:


> To explain, in order to satisfy the condition of *the same photo* (with the same dof) then subject distance, fov and _aperture diameter in mm_ *must* be held constant. In this instance _exposure_ *must* vary but focal length cancels out of the equation. But we do not take photos like this.



It's exactly how we take photos. We take photos with our attention on the content of the photo and not the peculiarities of the camera. We go on vacation and take landscapes from where we visited. We photograph the kids and the dog. We photograph our friends and our activities. And when we heap all the photos together there is deeper DOF on average in the photos if our camera has a smaller sensor/film and shallower DOF on average if our camera has a larger sensor/film. *No more evidence is needed than all the people with phone cameras who keep asking why they can't get blurry backgrounds in their pictures.*



Tim Tucker said:


> In your case you substitute _exposure_ for _aperture diameter in mm_ but still insist that other things must be held constant such as fov and subject distance and the conclusion is that sensor size affects dof, which it does not directly do.



The value for sensor size is no less direct or less integral than lens focal length.





Sensor size is just as integral a value in that equation as focal length. H (hyper focal distance), f (focal length), N (f/stop), c (circle of confusion). You can't remove any value from the equation and the value for c is directly derived from the size of the sensor (see chart below).




reference: Circle of confusion - Wikipedia

We take photos like this. A vacation landscape:





I show up to take that photo with my phone camera and you bring a FF DSLR. Click and click we take the same photo. Infinity is a limiting factor. Exposure is a limiting factor. The dirt road on the left is a limiting factor (looks bad) and the campground on the right is a limiting factor (ruins the composition).  So we take the *same photo* and at any given f/stop value hyperfocal distance is closer to me than to you, yes because I have a shorter lens focal length, *BUT ALSO* because the circle of confusion is a smaller value for my camera than yours and that's because my camera has a smaller sensor (see chart above).

Joe


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## Tim Tucker (Nov 18, 2016)

Ysarex said:


> I show up to take that photo with my phone camera and you bring a FF DSLR. Click and click we take the same photo. Infinity is a limiting factor. Exposure is a limiting factor. The dirt road on the left is a limiting factor (looks bad) and the campground on the right is a limiting factor (ruins the composition).  So we take the same photo and at any given f/stop value hyperfocal distance is closer to me than to you, yes because I have a shorter lens focal length, *BUT ALSO* because the circle of confusion is a smaller value for my camera than yours and that's because my camera has a smaller sensor (see chart above).
> 
> Joe



Joe, the circle of confusion is not a function of the sensor, it is not caused or defined by the sensor but the lens and primarily the diameter in mm of the effective aperture. Any camera with a smaller sensor uses a shorter focal length lens to take "similar" photos, (let's drop the "same" tag as I see what you mean). To maintain the same exposure you use the same f-stop which as a ratio of the focal length to effective aperture diameter means any similar photo shot on a smaller sensor with the same exposure is always using a narrower effective aperture. This is what affects the circles of confusion and gives the greater dof on smaller sensors.

If we make the assumption that two sensors have the same fov when one is shot with a 50mm lens and the other with a 35mm lens and that to maintain the same exposure (shutter speed and ISO the same) we use f4 on both. Then the image shot through the 50mm lens is shot through an effective aperture with a diameter of 12.5mm, and the image shot through the 35mm lens is shot through one of 8.75mm. With the fov being the same the smaller effective aperture limits the angle of light entering the lens making it more parallel and thus giving the greater dof. Exactly the same thing happens when we put the 35mm lens on the larger sensor, we get greater dof because of a shorter focal length and how it affects effective aperture while maintaining exposure. This effect is not in this case anything to do with sensor size but focal length, the optics and the change in the circles of confusion are the same in both cases. It's only when you specify "same photo with same fov" that you are forced to change sensor size _in proportion_ to focal length and it's this condition alone that brings sensor size into the equation. The relationships that govern dof work just the same when we do not take photos with the same fov.

The chart you show _defines_ circles of confusion used to calculate dof for various format sizes based solely on image magnification (the size defined in your chart is magnified x number of times) to a 10"x8" print to be viewed at a certain distance. It is because you magnify the image made by the smaller sensor more than that of a larger sensor that the circle of confusion must be smaller to create the same dof in the 10"x8" print. The sensor does not create them in any way, though the amount you have to enlarge the image is an integral part of calculating dof. (The decrease in dof through larger magnification of the smaller image is smaller than the increase in dof by the smaller effective aperture diameter).


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## petrochemist (Nov 18, 2016)

minicoop1985 said:


> The longer MM a lens is, for a given distance at same aperture, the DOF for the longer lens will be thinner.



Technically this is complete garbage.
MM has no meaning here at all, what you meant I think was the Focal length which is usually measured in mm - changing the letters to caps completely changes their meaning. Technically there is a length unit of Mm, which is a megameter, 1 billion times the length of a millimeter. I never met anyone using this unit perhaps because of the ease of confusion.
Millimeters would also be suitable units for the aperture (if not measured as a ratio) and the DOF.
Your incomplete maths describes some of the aspects controlling DOF but isn't really much help.

The DOF formula is (with all distance measurements should be done in the same units):
DOF = 2 *aperture * circle of confusion * subject distance²/focal length².

Aperture being the f-stop (a unit-less number derived from the focal length of the lens divided by diameter of the opening.) not the physical diameter of the opening itself.

'circle of confusion' being the distance between two dots that the viewing system can JUST resolve - it's dependent on the viewing size but with digital systems is often taken as being the pixel size on the sensor. If the camera is kept the same it can be simply considered a constant for comparing the other aspects. Which is probably a good thing as it promotes so many technical arguments!

The other bits should need no explanation.


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## Ysarex (Nov 18, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > I show up to take that photo with my phone camera and you bring a FF DSLR. Click and click we take the same photo. Infinity is a limiting factor. Exposure is a limiting factor. The dirt road on the left is a limiting factor (looks bad) and the campground on the right is a limiting factor (ruins the composition).  So we take the same photo and at any given f/stop value hyperfocal distance is closer to me than to you, yes because I have a shorter lens focal length, *BUT ALSO* because the circle of confusion is a smaller value for my camera than yours and that's because my camera has a smaller sensor (see chart above).
> ...



You mean the condition of taking photos with a camera. So according to you DOF is the same for all format cameras and they can all be used to take photos with DOF that appears the same. I'd like to see you make that work. The fact is that to take a photo you have a camera in your hand. Your ability to render DOF is in part a function of the size of that camera's recording media. How "direct" the effect doesn't matter in the end when the finished photo is viewed.

Take the OP's original photo. He wanted to claim the extreme shallow DOF was due to his long 150mm lens. But my 5.2mm lens took a photo with even shallower DOF. DOF is a function of magnification and f/stop when you simplify the equation. And when you simplify the equation note it no longer contains lens focal length as a "direct" determinant -- (just like sensor size is not "direct") since magnification is a function of focal length and subject distance. But FL is there and can't be removed. And you also can't remove sensor size from the determination of Coc. Although both values are not "direct" you can't complete a valid DOF calculation without a numerical value that represents focal length and you can't complete a valid DOF calculation without a numerical value that represents sensor/film size. *Show us otherwise. *Show us a DOF calculator or set of DOF equations that don't contain a value that represents the size of the sensor/film. *If Coc is in the equation it is representative in part of the sensor/film size; you cannot claim otherwise.*



Tim Tucker said:


> The relationships that govern dof work just the same when we do not take photos with the same fov.
> 
> The chart you show _defines_ circles of confusion used to calculate dof for various format sizes based solely on image magnification (the size defined in your chart is magnified x number of times) to a 10"x8" print to be viewed at a certain distance. It is because you magnify the image made by the smaller sensor more than that of a larger sensor that the circle of confusion must be smaller to create the same dof in the 10"x8" print.



*Duh...* And that is in fact how DOF is defined by our discipline -- viewed on a finished 10x8 print from a normal viewing distance. We have long since agreed on that -- no other definition makes practical sense. Modifications of the calculations exist if you want to run them through for a larger print size. You can find online calculators that accommodate (Cambridge in Colour) but you can't find a DOF calculator that doesn't use a value for Coc that is determined in reference to the sensor size. Show us otherwise.

Joe


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## Braineack (Nov 18, 2016)

Grabs popcorn, I love coc deniers

using tapatalk.


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## beagle100 (Nov 18, 2016)

OK


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## Derrel (Nov 18, 2016)

Background Blur and Its Relationship to Sensor Size

Background blur and its relationship to sensor size
*********


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## Derrel (Nov 18, 2016)

Keep in mind that depth of field is NOT the same thing as background blur!

Small-sensor cameras, like say the iPhone 7, or compact point & shoot digital cameras, can produce almost no real "background blur". Background blur is to a high degree, correlated with the actual, phusical WIDTH of the light-admitting aperture. The physically wider the aperture, the more blur that can be obtained; this becomes readily apparent when you use a 300mm f/2.8 lens, and shoot half-body portraits of a 6 foot tall person, using f/2.8 as the aperture value; the background on a half-body person is tremendously blurred. using an iPhone 7 at f/2.8, with anhalf-bopdy person shown in a standing shot, from the belt up to the top of their head, the SAME f/2.8 aperture produces a background that is not very blurred at all.


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## jcdeboever (Nov 18, 2016)

I need to smoke a doobie... anyone got one?


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## Tim Tucker (Nov 18, 2016)

Ysarex said:


> So according to you DOF is the same for all format cameras and they can all be used to take photos with DOF that appears the same.



No, the image formed at the sensor of light recording media is the same for the same focal length, f-stop and subject distance. Not the finished image.



Ysarex said:


> DOF is a function of magnification and f/stop when you simplify the equation. And when you simplify the equation note it no longer contains lens focal length as a "direct" determinant -- (just like sensor size is not "direct") since magnification is a function of focal length and subject distance.



When you simplify the equation then dof is a function of how parallel the light rays from a point object are passing through the lens, which is in turn a function of subject distance and _aperture diameter_, (minus the amount you have to magnify the image). Because we use exposure as constant then we use f-stop, the ratio of the focal length to aperture diameter and focal length affects it because it changes the effective aperture diameter. You can only remove focal length by using aperture diameter not f-stop, but of course that means that exposure must then vary across formats.

I did not remove sensor size from the equation, I said:



Tim Tucker said:


> There are four variables that affect dof; distance to subject, aperture, focal length, and image magnification. Focal length is irrespective of sensor size as the only variable here is image magnification for final viewing. A 150mm lens has the same dof on any sensor before you magnify the image



But you said:



Ysarex said:


> *BUT ALSO* because the circle of confusion is a smaller value for my camera than yours and that's because my camera has a smaller sensor (see chart above).



I am saying that in the statement above you confuse a correct understanding of dof. 

Now you can say that sensor size affects dof and you'd be correct. But to say that a smaller sensor has greater dof because sensor size is part of the equation mis-understands that the role of smaller sensors in the equation is to _decrease_ dof through extra magnification, not increase it. The smaller sensor does not have a smaller COC, the smaller sensor _needs_ a smaller COC in order to produce the same dof in the magnified image.

The increase, or smaller COC created _at the sensor_, is entirely a function of the optics and is independent of sensor size. That you generally use shorter focal length lenses with smaller sensors, (and smaller effective aperture diameters) is why they generally have greater dof. If you were to use sensor size as a way of controlling dof then you may come across the flaws mentioned above, and find that the effects of magnification of the image to final viewing size is quite small compared to the effects of using shorter focal lengths with smaller effective aperture diameters.


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## Ysarex (Nov 19, 2016)

Tim Tucker said:


> I did not remove sensor size from the equation, I said:
> 
> 
> 
> ...



And I'm saying that in this statement, "A 150mm lens has the same dof on any sensor before you magnify the image" you confuse a correct understanding of DOF. DOF is not defined at the sensor or film. There isn't any DOF on the sensor. DOF is defined in the final image.



Tim Tucker said:


> Now you can say that sensor size affects dof and you'd be correct.



That is all I said. Glad to see you agree. I said, "Don't forget the size of the recording media. All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."

And you said, "Not really. The difference in dof is due to the magnification of the image to the final viewed size. With all being equal then a 150mm lens will produce the same circles of confusion regardless of the sensor size, it's just how much you magnify it in the finished image, (and how that relates to viewing distance)."

Which confuses a correct understanding of DOF. DOF is not defined at the sensor or film. DOF is defined in the final image which includes magnifying the image to the standard final print size. Coc therefore is specified differently for different size formats.

*Trying to define DOF at/on the sensor or film is what trips people up and causes confusion.*



Tim Tucker said:


> But to say that a smaller sensor has greater dof because sensor size is part of the equation mis-understands that the role of smaller sensors in the equation is to _decrease_ dof through extra magnification, not increase it. The smaller sensor does not have a smaller COC, the smaller sensor _needs_ a smaller COC in order to produce the same dof in the magnified image.



You're nit picking in a salvage attempt. Yes, the Coc is not a property of the sensor. There is no DOF calculation that has a variable X = sensor size. I know that. But there is no DOF equation that does not have a variable c = Coc and in all of those equations that value for c is set relative to the sensor size. And that's what I mean when I say you can't remove sensor size from the equation. The smaller sensor _needs_ a smaller Coc that's fine. Point is you must use that smaller Coc for each progressively smaller sensor to do a valid DOF calculation.



Tim Tucker said:


> The increase, or smaller COC created _at the sensor_, is entirely a function of the optics and is independent of sensor size. That you generally use shorter focal length lenses with smaller sensors, (and smaller effective aperture diameters) is why they generally have greater dof. If you were to use sensor size as a way of controlling dof then you may come across the flaws mentioned above, and find that the effects of magnification of the image to final viewing size is quite small compared to the effects of using shorter focal lengths with smaller effective aperture diameters.



Never said a thing about which variables had the greater or lesser effect, that's off topic.

I think it comes down to this: You want to brush aside sensor size as accounted for in "image magnification" and consider image magnification as something occurring after DOF is determined. You think of DOF as defined at the sensor. I see that as confusion. I want to stick with tradition and be true to the equations we use to calculate DOF and that define DOF on the final print -- the way our discipline has done it since before we were both born. There are no standard equations to calculate DOF at the sensor. You can't find a DOF calculator that does that. Go to DOF Master or Cambridge in Colour and use the DOF calculators and they incorporate a value for Coc relative to the sensor size. Download one for your phone -- does the same thing.

Surely there's no argument that you get generally deeper DOF from smaller sensor cameras and shallower DOF from larger sensor cameras. Same was true with film and our traditional DOF equations reflect that. I'm a traditional kind of guy. So when understanding this equation:






I want to be able to say that the value of c changes with the size of the sensor which therefore appropriately reflects the phenomena that smaller format cameras have deeper DOF and vise versa. Sensor size therefore is a DOF determinant factor since you can't calculate DOF without it.

Joe


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## OGsPhotography (Nov 19, 2016)

Good thread, I am a circle of confusion now .


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## Tim Tucker (Nov 19, 2016)

In my very first example I threw out your condition of fov being constant and introduced focal length as being constant, and guess what happens? Dof decreases with smaller sensors. Now this is not the whole story, just as your examples are not the whole story, but your thesis that smaller sensors produce greater dof does not hold true in all cases. All I've been saying, and I think I've been quite clear about it, is that it's the use of shorter focal length lenses associated with smaller sensors and the use of smaller aperture diameters to maintain exposure, not the sensor size.



Ysarex said:


> I want to be able to say that the value of c changes with the size of the sensor which therefore appropriately reflects the phenomena that smaller format cameras have deeper DOF and vise versa. Sensor size therefore is a DOF determinant factor since you can't calculate DOF without it.



Just because a smaller sensor requires a smaller value for c does not mean that sensor size determines dof._ c_ is not dof or sensor size it is the limit for the size of the coc and nothing else. COC is entirely derived from the optics.

Smaller sensors actually have a negative effect on dof, they decrease it. It's only when you reduce the aperture diameter or increase subject distance that dof increases, if you simply reduce sensor size and hold focal length, subject distance and aperture constant then dof _decreases_ with a smaller sensor.

1) If you have a set up where all you change is the camera body for one of a smaller sensor (the optics, exposure and subject distance remain the same), the dof decreases with the smaller sensor.

2) If you change the lens for a shorter focal length, (sensor size, exposure and subject distance remain the same), then dof increases.

Now if you do both, (change the sensor size to a smaller one and change the lens for one of a shorter focal length but maintain fov, subject distance and exposure constant), then the extra magnification needed for the smaller sensor decreases dof and the use of a shorter focal length (and the smaller aperture diameter to maintain exposure) increases it, but does so to a much larger extent. The size of the COC does not change with sensor size, it only changes with subject distance, f-stop and focal length, (or subject distance and aperture diameter, _but please note that to maintain exposure it is much better to use f-stop and therefore it is subject distance, f-stop and focal length_). The only effect sensor size has is in the magnification to the final reference print, and smaller sensors need greater magnification.

I cannot be clearer.

(Seeing as the value of c is directly derived from the sensor size it is no surprise that it changes with sensor size, x + y = z then z - y = x, it's nothing to do with the lens!)


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## Ysarex (Nov 19, 2016)

Tim Tucker said:


> In my very first example I threw out your condition of fov being constant and introduced focal length as being constant, and guess what happens? Dof decreases with smaller sensors.



No need to guess, of course that's obvious. There is no point in comparing different photos. If you put a 165mm Angulon on an 8x10 camera and shoot the Grand Tetons that photo will have more DOF than a macro photo of a fly taken with a 165mm lens on a 35mm camera. Duh... so what.

The only comparison that makes any logical sense is to take the same photo.



Tim Tucker said:


> Now this is not the whole story, just as your examples are not the whole story, but your thesis that smaller sensors produce greater dof does not hold true in all cases.



It's not a thesis it's proven and accepted fact. Here's a reference: "*'Same picture' for both formats*
When the 'same picture' is taken in two different format sizes from the same distance at the same _f_-number with lenses that give the same angle of view, and the final images (e.g., in prints, or on a projection screen or electronic display) are the same size, DOF is, to a first approximation, inversely proportional to format size (Stroebel 1976, 139)." Depth of field - Wikipedia

Notice the reference to Stroebel. That would be Leslie Stroebel and his definitive text _View Camera Technique. _I'm not going to type the whole paragraph so I took a snapshot (page 130 5th edition):








Tim Tucker said:


> All I've been saying, and I think I've been quite clear about it, is that it's the use of shorter focal length lenses associated with smaller sensors and the use of smaller aperture diameters to maintain exposure, not the sensor size.



Chicken and egg argument and you're claiming the egg doesn't matter which is irrational.



Ysarex said:


> *I want to be able to say that the value of c changes with the size of the sensor*





Tim Tucker said:


> But you can't, because it doesn't.



Then you need to change the Wikipedia article on Circle of Confusion and get this chart out of there:





And then you need to contact Dan Fleming at DOFMaster and get him to remove this page: Circles of Confusion for Digital Cameras Because they're changing the Coc value predicated on the size of the format.



Tim Tucker said:


> _c_ is not dof or sensor size it is the limit for the size of the coc and nothing else. You cannot equate something that is entirely derived from the optics as being a function of the sensor.



I never claimed Coc was a function of the sensor. I know better. I said that in an equation used to calculate DOF the value of Coc is selected predicated on the size of the recording media. I remain correct. I also said you can't find a DOF calculator that doesn't work that way. I posted this earlier:





Please note the two different values for Circle of confusion. They are different because the sensor sizes are different, an FX and DX camera. Please provide a link to an online DOF calculator that doesn't do that.



Tim Tucker said:


> Smaller sensors actually have a negative effect on dof, they decrease it. It's only when you reduce the aperture diameter that dof increases, if you simply reduce sensor size and hold focal length and aperture constant then dof _decreases_ with a smaller sensor.
> 
> 1) If you have a set up where all you change is the camera body for one of a smaller sensor (the optics, exposure and subject distance remain the same), the dof decreases with the smaller sensor.


Two different photographs and so no comparison being made -- no meaning.



Tim Tucker said:


> 2) If you change the lens for a shorter focal length, (sensor size, exposure and subject distance remain the same), then dof increases.


Two different photographs and so no comparison being made -- no meaning.



Tim Tucker said:


> Now if you do both, (change the sensor size to a smaller one and change the lens for one of a shorter focal length but maintain fov, subject distance and exposure constant), then the extra magnification needed for the smaller sensor decreases dof and the use of a shorter focal length (and the smaller aperture diameter to maintain exposure) increases it, but does so to a much larger extent.



*Same photo and deeper DOF in the final print from the smaller sensor camera. Yep, that's what I've been saying.*



Tim Tucker said:


> The value of _c_ does not change with sensor size,



In all equations used to calculate DOF the value of c is changed when the size of the sensor is changed. That's obvious from the screen shots above. Please provide a link to a DOF calculator that  doesn't do that. That doesn't mean that Coc is a function of sensor size. It doesn't mean that sensor size alters the physics of optics. It simply means that we can't calculate DOF without a value that references the size of the sensor. An accommodation in the equation is made to account for the size of the sensor. Please provide a link to an online DOF calculator that doesn't do that.

Same hang-up, you're trying to calculate DOF at the sensor. It's not defined that way. You can't calculate DOF without including a value that is predicated in part on the size of the sensor. As such changing the size of the sensor changes the result of the calculation. Show us a calculator that doesn't do that.

Pragmatically one more time: Take the "same photo" with two cameras of different sensor size and the photo from the smaller sensor camera will have deeper DOF. *You just said that above and that's what I originally said,* and the equations that are used to do that calculation include a value predicated on that sensor size. Show us a DOF calculator that doesn't do that.

I didn't say Coc is a function of sensor size. I didn't even say that Coc changes optically when we change the sensor size. *We change* the value of Coc in the equations when we change sensor size. We get more accurate and practically useful results from the equations when we do that. We don't calculate DOF any other way -- *can't calculate DOF without a value referenced to the sensor size and so sensor size is a DOF determinant.*

Joe



Tim Tucker said:


> it only changes with subject distance, f-stop and focal length, (or subject distance and aperture diameter, _but please note that to maintain exposure it is much better to use f-stop and therefore it is subject distance, f-stop and focal length_). The only effect sensor size has is in the magnification to the final reference print, and smaller sensors need greater magnification.
> 
> I cannot be clearer.


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## Derrel (Nov 19, 2016)

I was at the library for a couple of hours earlier this week. I picked up a book by a well-known photographer, and in it I found a little graphic that had some distilled wisdom. In this graphic, he said that for "*storytelling pictures*", apertures of f/16 and f/22 were often the most useful.

For single-themed or single-subject images, he suggested apertures of f/4 and f/5.6 were often useful.

For subjects where depth of field was not normally a significant factor, he suggested f/8 and f/11.

In another area of the book, he mentioned that when shooting a lens wide-open, "What you see through the viewfinder is basically, what you will get."


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## Ysarex (Nov 19, 2016)

Derrel said:


> I was at the library for a couple of hours earlier this week. I picked up a book by a well-known photographer, and in it I found a little graphic that had some distilled wisdom. In this graphic, he said that for "*storytelling pictures*", apertures of f/16 and f/22 were often the most useful.
> 
> For single-themed or single-subject images, he suggested apertures of f/4 and f/5.6 were often useful.
> 
> ...




Yes, and thank you for that reminder.

One of the reasons I'm toughing this one out is that it's really useful to have general rules that hold true. One of those general rules is that cameras with smaller sensors/film generally produce photos with deeper DOF and cameras with bigger sensors/film generally produce photos with shallower DOF. It's not a huge difference when stepping from one camera to next size, but it is a substantial difference say between an M4/3 and old sheet film camera. This is a helpful general rule to know and to know the rule requires that we identify the role of the sensor/film size in determining DOF. It's helpful to be able to state the rule simply and directly. This one is a winner in that regard.

Joe


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## Derrel (Nov 19, 2016)

I should probably have mentioned, the famous photographer mentioned above shoots mostly with APS-C Nikons, and FX Nikons. The book has mostly "new" work in it, from the Nikon D300s (APS-C), and then the Nikon D3x, and finally, the Nikon D800e or D810 (all three of which are 24x36mm sensor sized). The majority of the images were made with a 24-85mm Nikkor lens; a 105mm Nikon macro lens, and the Nikon 70-300 VR lens, all three of which are pretty common lenses, affordable by the majority of enthusiasts.

I was not too surprised to see many,many good pictures made with the 24-85 zoom lens, and with the light-in-weight 70-300mm VR lens.

While many people fuss over using f/16 and f/22 due to softening caused by diffraction, my personal experiene is that the deeper depth of field that can be obtained by stopping down to f/16 or f/22 on a 24x36mm sensor, or a smaller sensor like APS-C, is in many ways, sort of a theoretical worry more so than the disastrous "ruiner of pictures" so many internet folks seem to classify the small f/stops as being! I totally, totally understood what he meant by suggesting f/16 and f/22 for "*storytelling pictures*".


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## Bebulamar (Nov 24, 2016)

Ysarex said:


> Bebulamar said:
> 
> 
> > Didn't see any bokeh in either posted images. Lack of Depth of Field isn't a good thing.
> ...



I don't see the bokeh. The blur isn't all that good to call bokeh. Both photo lack depth of field that is the depth of field is too narrow.


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## Ysarex (Nov 24, 2016)

Bebulamar said:


> Ysarex said:
> 
> 
> > Bebulamar said:
> ...



bo·keh
bōˈkā/
_noun_
Photography
noun: *bokeh*
the visual quality of the out-of-focus areas of a photographic image, especially as rendered by a particular lens.

If there's blur, and there is, then it has a visual quality. It doesn't become bokeh only when you like the visual quality. If a photo's depth of field is "too narrow" then there must be depth of field so the photo can't lack depth of field.

Joe


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## Derrel (Nov 24, 2016)

The word *bokeh *was originally brought to the entire English-speaking world back in the late 1990's. Searches on-line using The Online Photographer + bokeh will reveal several good hits. Perhaps THE best search result is Mike Johnston's 2009 post about what bokeh is, and what it is not. Found at   What Is Bokeh?

A brief excerpt: "The original articles about bokeh were published in the March/April 1997 issue of _Photo Techniques_ magazine, which I edited at the time. (Long sold out, unfortunately.) Carl Weese introduced me to the term. The articles were written by John Kennerdell, Oren Grad, and Harold Merklinger. Harold's article is onlineat The Luminous Landscape. Oren and John still write for me on occasion here at The Online Photographer (John just the other day). The only reason we added the "h" to the end of the Japanese word in the magazine was that English speakers persistently mispronounce "boke." It's properly pronounced in two syllables, "bo" as in "bone" and "ke" as in "Kenneth" with equal stress on each syllable. "Bokeh" simply renders that a little more accurately. At least adding the "h" stopped all the "toke" and "smoke" jokes. Er, and the "joke" ones."

Additional excerpt: "
*ADDENDUM:* Just to further clarify the terminology: 

*Boke:* _Japanese for "out-of-the-depth-of-field blur" or "out-of-focus blur."_
*"Out-of-the-depth-of-field blur"* or *"out-of-focus blur":*_English for_ boke.
*Boke-aji:* _Japanese for "flavor of blur," i.e., what kind of_ boke _it is or how the_ boke _might be described._
*Bokeh:* _Alternate spelling of _boke _meant to forestall mispronunciation._
*Selective focus:* _Tactic by photographers of deliberately putting some parts of a picture in sharp focus and other parts not._
*Poor focusing:* _Indiscriminate or inadvertent misfocus."_


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## Didereaux (Nov 26, 2016)

Ok  Here is my contribution.  This photo has what I consider excellent bokeh, it is done with a super telephoto at med aperture,    the second photo gives an excellent example of DoFand is using a med zoom 70-200 lens..

Merlin magic in Nature forum  F7.1 @600mm






Snowy on a railing BW GAllery  F4  70-200@200  the bird was about 50' away.


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## Tim Tucker (Nov 29, 2016)

So I say _c_ when I mean COC.

Also I have been very busy hence the no reply, (having to finish building the new house so we could move in as we had notification that the purchasers wanted to complete in 5 days which thankfully fell through).

But my real problem with your argument (that smaller sensors give greater dof) is and always has been this:



Ysarex said:


> The only comparison that makes any logical sense is to take the same photo.



Why? Why do you insist that the only comparison that you can make has some very real limitations as to what you can compare? You will only make a comparison when you _*change focal length and aperture diameter in exact proportion to the change in sensor size*_ and will not consider any other comparison.

So what? With that condition you can say that dof is proportional to sensor size, (though it is not sensor size that controls it), but in all other cases it is not. So you cannot say that when you impose the restriction that you *change focal length and aperture diameter in exact proportion to the change in sensor size *that smaller sensors produce larger dof *when that restriction is removed* because they do not.

Entertain me a little longer. 

I said, a lot earlier on, that the relationships regarding dof are beautifully symmetrical. You change one thing and another has to change by an equal amount. It also hold true that if you hold one thing constant, (such as fov) then the others *have* to change in an *exact proportion* to each other.

If you maintain constant effective aperture diameter (equivalent aperture, but I do not hold with the use of it though the maths is correct) then with truly equivalent photos the smaller sensor will alway produce a smaller dof simply because you have to magnify the latent image more. If you use the same lens at the same _f_-stop (exactly equivalent aperture) on two sensors then the smaller will have less dof because of image magnification

From Wikipedia (Depth of field - Wikipedia):

*Relationship of DOF to format size[edit]*
_The comparative DOFs of two different format sizes depend on the conditions of the comparison. The DOF for the smaller format can be either more than or less than that for the larger format. In the discussion that follows, it is assumed that the final images from both formats are the same size, are viewed from the same distance, and are judged with the same circle of confusion criterion. (Derivations of the effects of format size are given under Derivation of the DOF formulas.)
_
*"Same picture" for both formats[edit]*
_When the "same picture" is taken in two different format sizes from the same distance at the same f-number with lenses that give the same angle of view, and the final images (e.g., in prints, or on a projection screen or electronic display) are the same size, DOF is, to a first approximation, inversely proportional to format size (Stroebel 1976, 139). Though commonly used when comparing formats, the approximation is valid only when the subject distance is large in comparison with the focal length of the larger format and small in comparison with the hyperfocal distance of the smaller format.

Moreover, the larger the format size, the longer a lens will need to be to capture the same framing as a smaller format. In motion pictures, for example, a frame with a 12 degree horizontal field of view will require a 50 mm lens on 16 mm film, a 100 mm lens on 35 mm film, and a 250 mm lens on 65 mm film. Conversely, using the same focal length lens with each of these formats will yield a progressively wider image as the film format gets larger: a 50 mm lens has a horizontal field of view of 12 degrees on 16 mm film, 23.6 degrees on 35 mm film, and 55.6 degrees on 65 mm film. Therefore, because the larger formats require longer lenses than the smaller ones, they will accordingly have a smaller depth of field. Compensations in exposure, framing, or subject distance need to be made in order to make one format look like it was filmed in another format.
_
*Same focal length for both formats[edit]*
_Many small-format digital SLR camera systems allow using many of the same lenses on both full-frame and "cropped format" cameras. If, for the same focal length setting, the subject distance is adjusted to provide the same field of view at the subject, at the same f-number and final-image size, the smaller format has greater DOF, as with the "same picture" comparison above. If pictures are taken from the same distance using the same f-number, same focal length, and the final images are the same size, the smaller format has less DOF. If pictures taken from the same subject distance using the same focal length, are given the same enlargement, both final images will have the same DOF. The pictures from the two formats will differ because of the different angles of view. If the larger format is cropped to the captured area of the smaller format, the final images will have the same angle of view, have been given the same enlargement, and have the same DOF.
_
As you quote, in the only example you will consider for comparison, that you must also change focal length and aperture diameter in exact and unvarying proportion to maintain your rule of same photo, then might it not possibly be one of those that gives the true explanation of why using smaller sensor cameras generally gives larger dof? If you look at one thing at a time and adjust one thing at a time then you will find the following:

Reducing sensor size and keeping as many other variables constant will generally result in _*reduced*_ dof.

In all cases reducing effective aperture diameter and keeping as many other variables constant will generally result in _*increased*_ dof.

As I said before, to maintain exposure on a smaller sensor with a shorter focal length lens you must use the same _f_-stop which is a smaller effective diameter and it is this that gives the increased dof not the sensor size. The sensor size actually has a negative effect on dof.

Lenses create COC dependant on subject distance and effective aperture diameter, (focal length/_f_-stop), shorter focal length lenses have smaller effective aperture diameters at the same _f_-stop. COC is magnified dependant on sensor size, the smaller the sensor the more magnification needed reducing dof.

You originally argued that smaller sensors gave greater dof, I argue that they do not, in fact smaller sensors decrease dof and it is the smaller effective aperture diameters used with the shorter focal length lenses to maintain _f_-stop (exposure) that account for the increased dof.

_EDIT: It's interesting to note that smaller sensors do not have always have greater dof even when you impose the condition of same photo and same exposure, it is at best only an approximation that works for middle focussing distances.
If you consider the extreme of  shooting the stars, then with the subject at infinity (light from the subject is parallel) everything is in focus regardless of the format, f-stop and focal length, dof is the same in this case. 
As you get progressively more distant when focusing you will get to a point where the dof from both formats is very similar (past the near limit for the hyper-focal point for infinity in the smaller format there is no further increase in dof but the larger format continues to improve and can actually have better dof than the smaller format as it's magnified less).  Again it comes down to how much you magnify the 'latent' image to the final size and the smaller sensors are magnified more._


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## Ysarex (Nov 30, 2016)

Tim Tucker said:


> So I say _c_ when I mean COC.
> 
> Also I have been very busy hence the no reply, (having to finish building the new house so we could move in as we had notification that the purchasers wanted to complete in 5 days which thankfully fell through).
> 
> ...



Same spurious rational.
Explanation already given in previous post.
In previous post you were asked a question. *Please answer it.*
I'll repeat it for you: "_In all equations used to calculate DOF the value of c is changed when the size of the sensor is changed. That's obvious from the screen shots above. Please provide a link to a DOF calculator that doesn't do that. That doesn't mean that Coc is a function of sensor size. It doesn't mean that sensor size alters the physics of optics. It simply means that we can't calculate DOF without a value that references the size of the sensor. An accommodation in the equation is made to account for the size of the sensor. Please provide a link to an online DOF calculator that doesn't do that.

*Same hang-up, you're trying to calculate DOF at the sensor. It's not defined that way.* You can't calculate DOF without including a value that is predicated in part on the size of the sensor. As such changing the size of the sensor changes the result of the calculation. Show us a calculator that doesn't do that."
_
Please provide a link to or show us a DOF calculator that does not alter the value of CoC relative to format size. In other words show us a *DOF calculator that doesn't account for sensor size in the MATH used to calculate DOF.
*
Waiting for your answer.

_------------------------------------------------------------------------------_



Ysarex said:


> The only comparison that makes any logical sense is to take the same photo.





Tim Tucker said:


> Why? Why do you insist that the only comparison that you can make has some very real limitations as to what you can compare?


Because that's what the word compare means. Duuuuh. An analogy: Let's compare the suitability of two different woods; poplar and cherry. Let's use the cherry to make a musical instrument -- a wooden flute, and the poplar to make a kitchen cutting board. And now we compare the suitability of the woods. Can you see where we went wrong?

Common photo knowledge: Smaller format cameras generally produce photos with deeper DOF when compared with larger format cameras. True/false?

The appropriate test for this common photo knowledge: Give an Olympus Pen m4/3 camera to photo group A (5,000 people) and a Nikon D800 to photo group B (5,000 people). All participants are instructed to take 10,000 photos in a month of the "world that surrounds them." All live similar lives. They go to work, they spend weekends with the family, etc. etc. All participants are free to use lenses as they see fit but are reminded of the instruction to take general photos that depict their world. Compare the 50,000,000 photos *as a whole* from each group and *in general* the photos in group A will exhibit deeper DOF than the photos in group B. True/false?

Joe


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## robbins.photo (Nov 30, 2016)

Oh goodie.  Another Bokeh Brawl.  Back in a couple, need popcorn.


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## robbins.photo (Nov 30, 2016)

Ok, so quick suggestion to the admins, could we just put bokeh (and all related spellings) into the profanity filter, so from now on when someone tries to start a simple thread about DOF the term just gets asterisked out?


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## astroNikon (Nov 30, 2016)

robbins.photo said:


> Ok, so quick suggestion to the admins, could we just put bokeh (and all related spellings) into the profanity filter, so from now on when someone tries to start a simple thread about DOF the term just gets asterisked out?


that would put the popcorn manufacturers out of business.


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## robbins.photo (Nov 30, 2016)

astroNikon said:


> that would put the popcorn manufacturers out of business.



True, but it's a rerun.


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## Derrel (Nov 30, 2016)

Ysarex said:
			
		

> Common photo knowledge: Smaller format cameras generally produce photos with deeper DOF when compared with larger format cameras. True/false?
> 
> Joe



A resounding, emphatic TRUE! in the 1970's Kodak in point of fact, invented an entirely BRAND-NEW, ultra-tiny negative area film FORMAT, to get hyperfocal depth of field that extended from approximately 3 feet to Infinity, at around f/8, with the incredibly teeny-tiny Kodak Disc Format.

The negative size of 110 cartridge film (about the size of an old-school USA postage stamp) was too LARGE of a format for snapshot cameras, and many,many images inside of 6 feet were out of focus on low-end cameras. Kodak scientists understood that the easiest way to achieve a focus-free camera with almost infinite depth of field was to make the film size much smaller. Interestingly....the size of the Disc Format was about the same size as the sensor in an iPhone.

The story of this was related in a lengthy piece written by Herbert Keppler, the long time editor at Modern photography, and then the new, combined version of Modern photo and Popular Photography magazines.

Small-format cameras, like the Kodak Disc Camera, or the Apple iPhone, take photos that have VERY expansive, deep depth of field in everyday situations, at f/8 or f/9 or f/10, or even at f/2.8 with the iPhone; the teeny-tiny sensor in these types of cameras provides deep DOF, even at relatively fast f/stops, like f/2.8 at distances like 6 feet. With something like an 8x10 film camera, you'd be lucky to get the tip of the nose to the back of the head in-focus on a portrait shot with a 360mm lens set to f/8; on large-format film like 4x5, I ALWAYS started thiking of around f/22, may f/32, maybe f/45, or f/64 if needed, to get decent DOF on small-product shots. With an iPhone, I could snap the same pictures and get immense DOF at f/4.5.


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## Tim Tucker (Nov 30, 2016)

Ysarex said:


> Because that's what the word compare means. Duuuuh. An analogy: Let's compare the suitability of two different woods; poplar and cherry. Let's use the cherry to make a musical instrument -- a wooden flute, and the poplar to make a kitchen cutting board. And now we compare the suitability of the woods. Can you see where we went wrong?



You still don't get it do you? You're saying _y=x_ but in your proof you're specifying that the condition y=x must be met to be a valid comparison. I'm not making kitchen boards out of sugared cherries but explaining the flaws in your theory because you seem hell bent on linking smaller sensors to greater dof when all the evidence says it is the smaller effective aperture diameters that create greater dof, the smaller sensors do _*not*_ always have greater dof.

I've shown you where your model breaks down, I've shown you where larger formats have greater dof, I've shown you the two variables that are consistent with increasing and decreasing dof and yet you still dismiss them as invalid because they do not fit your theory.



Ysarex said:


> n other words show us a *DOF calculator that doesn't account for sensor size in the MATH used to calculate DOF.*



*Of course dof calculators account for sensor size!!!* _c_ is directly defined by dividing the finished print size by the sensor size, that's how you calculate _c_! But please note that the smaller the sensor then the less dof for any given COC, by your very own maths as you've presented???



Ysarex said:


> Same hang-up, you're trying to calculate DOF at the sensor.



*NO!!!!* I am not trying to calculate dof at the sensor at all. I'm fully aware of dof and what it is.

Basics.





Light is reflected of two point objects at different distances to the lens. The lens then bends each "ray of light" by an equal amount. If you adjust the focus so the light from the distant object is focussed on a point on the sensor then the light from the nearer object will be focussed beyond it creating a "circle of unfocussed light at the plane of the sensor (COC).

These are point light sources focussed on a plane. Fov does not come into the equation here. The COC formed at the sensor is independent of sensor size.

The image at the sensor is then magnified to produce the final print at the designated size for determination of dof, etc...

Now I'm completely failing to see how a smaller sensor can possibly produce greater dof here. With my maths the smaller sensor needs more magnification, and the more you have to magnify an image to produce a 10"x8" print then the more you'll magnify the COC s formed at the sensor and reduce dof.

Yet within a range of focusing distances (as explained before it's really noticeable at portrait distances for landscapes the larger formats can have either more or less dof, in short they are more adjustable) smaller sensor cameras appear to have greater dof (appear because dof is an illusion).

So what causes it? If reducing sensor size has a negative effect on dof, *which it clearly does*, then there must be something else at work.

One thing controls dof: the more parallel the light from the two point objects at different distances is when entering the lens then the more parallel it is when leaving the lens and thus the smaller the COC produced at the sensor is for the out of focussed object.

Two things affect this and neither are sensor size. The more distant the objects are then the more parallel the light coming from the two point object will be entering the lens (just move both objects back away from the lens in my above diagram and see what happens).

The smaller the effective aperture diameter is in front of the lens then the more parallel the rays passing through them lens from the two point objects will be (try introducing a smaller aperture in the diagram above and see what happens).

Sensor size does not affect any of this. In fact all I see is that the smaller the sensor is then the more you have to magnify the COC produced on the said sensor thus reducing apparent dof. To me this is simple and plain.

Now with your example of same photo and same exposure. You set the conditions of constant fov and constant _f_-stop. You will not compare _f_5.6 against _f_5.7 or an fov of 36 degrees against 35 degrees. You specify and set the condition of the test that comparison must be made only when the effective aperture diameter is adjusted in exact proportion, and so to compensate, to the change in sensor size. Then you tell me that I cannot rule sensor size out of the equation because it's a condition that you specify must be met before you even evaluate the results. _(To achieve the same fov on different formats then you *must* reduce focal length.  f-stop (exposure) is the ratio of the focal length to the aperture diameter. So to maintain fov across sensors you *must reduce the effective aperture diameter in exact proportion to the sensor size.* This is the condition that you have set, this is the condition that you will not deviate from, this is the only condition that you will accept as a valid test and because the condition of the test you have set inextricably linked sensor size to effective aperture diameter you say you've proved that smaller sensors have greater dof.)_


So what happens when you don't meet that specific proportion? What happens when the photos on the two sensors are not exactly the same and are just slightly different, (much like real photography)? What happens when we change sensor size while maintaining the effective aperture diameter? (_Smaller sensors have less dof_). What happens when we reduce the effective aperture diameter while maintaining sensor size? (_Dof increases_).

Can you see a simple rule that holds true in all cases yet? (_Dof is proportional to the subject distance and effective aperture diameter, [distance, f-stop and focal length], not sensor size_).



Derrel said:


> A resounding, emphatic TRUE! in the 1970's Kodak in point of fact, invented an entirely BRAND-NEW, ultra-tiny negative area film FORMAT, to get hyperfocal depth of field that extended from approximately 3 feet to Infinity, at around f/8, with the incredibly teeny-tiny Kodak Disc Format.



Yes, but as I stated before, once you get passed this hyper-focal distance then  the dof of the smaller sensor does not improve, yet the dof on the larger sensor does improve. So at _f_8 with the closest subject at a distance of say 300' (landscape) to infinity is the extra dof of a smaller sensor an advantage, or would you actually get better results from a larger sensor that needs less magnification to the finished print?

This is the very real limit of smaller sensors, that when you hit that hyper-focal distance there is less improvement in stopping down than you get from a large sensor. The gap closes and in some instances the larger sensors are better because they require less magnification. I ran into this wall very often when I briefly used APS-C cameras. Not because I wanted to increase dof but because with the kit lens once your subject exceeds the hyper-focal distance it is very difficult to decrease dof!


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## Derrel (Nov 30, 2016)

A lot of diagrams and text, but most unconvincing to me in this discussion. Sorry. Not interested in hearing your point of view, since it is at odds with what I know, and what thousands and thousands of experts know. Depth of field from 300 feet to Infinity? I could give a crap.


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## Tim Tucker (Nov 30, 2016)

Derrel said:


> A lot of diagrams and text, but most unconvincing to me in this discussion. Sorry. Not interested in hearing your point of view, since it is at odds with what I know, and what thousands and thousands of experts know. Depth of field from 300 feet to Infinity? I could give a crap.



I'm simply saying that the smaller sensor looses it's dof advantage once you get past the hyper-focal distance to infinity. In short and simply terms it does not have more dof than larger formats (whether you give a crap or not) when the dof of the subject is within the range of the larger formats, and everything at distance comes within the range of dof for the larger formats so smaller sensors only have greater dof over a limited range of portrait to middle distance. This is simple, (and well documented), stuff whether you want to believe it or not.

Thousands of experts will agree with it.

I'm sorry you felt compelled to give the reply you did.


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## pixmedic (Nov 30, 2016)

the circle of confusion is in my head. 


i am the walrus. 


coo coo ka-choo. 


just out of curiosity, (and since i have been totally lost since math was introduced into the conversation) is there any usefulness to DOF from the hyper-focal distance to infinity? is that an area where I am likely to look at in a photo?


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## The_Traveler (Nov 30, 2016)

The entire thread - tldr


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## snowbear (Nov 30, 2016)

The_Traveler said:


> The entire thread - tldr


Summary: 
DOF,
Bokeh,
Sensor Size,
Confusion Circles,
Popcorn


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## Derrel (Nov 30, 2016)

This thread was originally about depth of field and, ostensibly, about *bokeh*.  I think unfortunately, the original post might not have been created so as to create much of a fruitful discussion. Depth of field and bokeh are, really, two very different subjects. Very,very,very different subjects.

Bokeh, as in the out-of-focus areas of a photography--I gave a good reference to the Americanized word *bokeh*, from the actual web-blog post written by the _original magazine editor who introduced the Japanese word _*boke *to the English-speaking world_, but with an "h" added to the end of the Japanese-language word_, so as to prevent bad pronunciation of the word, way back in the 1990's (Hint: *bokeh* does not rhyme with toke,or joke, or smoke).

Unfortunately,for the most part, the subsequent replies to the original post have in some cases, devolved into mathematically-based examples of a most unhelpful nature, with very little emphasis on *bokeh*, or what it is, or what it looks like.

As to the questions, "Is there any usefulness to DOF from the hyper-focal distance to infinity? is that an area where I am likely to look at in a photo?" The answer to those two questions, I would think, are pretty self-evident, as an emphatic "Not much", and, "Not very likely."

If ever there were a TPF thread that ought to be closed, soon, this one qualifies. Split depth of field up and separate it, from the subject of *bokeh*. Go back to the actual SOURCE material on bokeh, and stay away from the Wikipedia definitions of it; as Mr. Johnston himself has written about the entire subject of bokeh, _his very own words on the subject of _*bokeh*_, have on numerous occasions, been re-written by Wikipedia's so-called "experts"_.


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## Ysarex (Nov 30, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > Because that's what the word compare means. Duuuuh. An analogy: Let's compare the suitability of two different woods; poplar and cherry. Let's use the cherry to make a musical instrument -- a wooden flute, and the poplar to make a kitchen cutting board. And now we compare the suitability of the woods. Can you see where we went wrong?
> ...



I never said smaller sensors always have greater DOF.  *Show me where I said that.* You're arguing with the words you put in my mouth.

*


Tim Tucker said:



			Of course dof calculators account for sensor size!!!
		
Click to expand...

*


Tim Tucker said:


> _c_ is directly defined by dividing the finished print size by the sensor size, that's how you calculate _c_! But please note that the smaller the sensor then the less dof for any given COC, by your very own maths as you've presented???



Yes, the math requires an accommodation for sensor size. That's all I ever really said: _"Don't forget the size of the recording media. All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."_ *You can't do the math and calculate DOF without including the size of the sensor and so sensor size is a factor in determining DOF. When used to take the same photo the smaller format camera will produce deeper DOF.*

This fact that the smaller sensor camera produces deeper DOF when used to take the same photo is appropriate as a general rule. And this is what matters to photographers. Photographers take photographs and if they're comparing cameras they want to know how they'll perform when used for the same application.

I completely understand that a smaller format camera REQUIRES shorter lenses in general use. That set to the same f/stop the effective aperture diameter of a shorter lens is smaller than a longer lens. I get that. But the fact that smaller format cameras do REQUIRE shorter lenses in order to have generally useful fields of view means that smaller format cameras generally take photos with deeper DOF than larger format cameras.

This is true: Smaller format cameras generally produce photos with deeper DOF when compared with larger format cameras.

This is true: Give an Olympus Pen m4/3 camera to photo group A (5,000 people) and a Nikon D800 to photo group B (5,000 people). All participants are instructed to take 10,000 photos in a month of the "world that surrounds them." All live similar lives. They go to work, they spend weekends with the family, etc. etc. All participants are free to use lenses as they see fit but are reminded of the instruction to take general photos that depict their world. Compare the 50,000,000 photos *as a whole* from each group and *in general* the photos in group A will exhibit deeper DOF than the photos in group B.

And because that's true I'm going to continue to affirm this: *You can't do the math and calculate DOF without including the size of the sensor and so sensor size is a factor in determining DOF. When used to take the same photo the smaller format camera will produce deeper DOF.
*
My rationale for presenting this in this form is because it is useful and helpful for photographers. _"All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."_

Joe


----------



## robbins.photo (Dec 1, 2016)

pixmedic said:


> the circle of confusion is in my head.
> 
> 
> i am the walrus.
> ...



Hi, Eggman here...

So, reading through all of this.. er, well reading through some of this and just skimming over the charts and graphs and the pictures with the circles and the arrows and such...

It occurs to me that whenever anyone uses the term "bokeh" they almost always use it incorrectly, or at the very least they don't take the time to put in a 45 page dissertation explaining precisely what they mean by using the term.

Then someone else comes along and in an effort to prove their superior subject knowledge, just can't resist the impulse to offer a correction.  That correction is then corrected again and before you know it we've got a knock down drag out on our hands.  Charts and graphs are flying everywhere... dogs and cats living together.  Basically the worst parts of the bible.

Ok, so for the folks that are arguing the EXTREMELY FINE points here, just stop and ask yourselves, do you honestly think any of this is any way really useful or even understandable to the average photographer in the field?  If you really believe that, can you post a simple, one paragraph explanation of why without using any charts, graphs or equations?

If not, then maybe it's time we all put our professor hats away and move on.

This has been a community service message from your local Eggman.


----------



## Tim Tucker (Dec 1, 2016)

Ysarex said:


> Yes, the math requires an accommodation for sensor size. That's all I ever really said: _"Don't forget the size of the recording media. All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."_ *You can't do the math and calculate DOF without including the size of the sensor and so sensor size is a factor in determining DOF. When used to take the same photo the smaller format camera will produce deeper DOF.*
> 
> This fact that the smaller sensor camera produces deeper DOF when used to take the same photo is appropriate as a general rule. And this is what matters to photographers. Photographers take photographs and if they're comparing cameras they want to know how they'll perform when used for the same application.



And I'm saying that there are too many examples where this is not true for it to be held as a general rule. The rule that dof is proportional to sensor size only really works of the same photo example (same fov, same subject distance and same _f_-stop) and only holds valid at portrait distances.

Below are some examples of an actual photos of many I have to illustrate the point because it's common in landscape photography. I will continue to use your same photo example (same fov, same subject distance and same _f_-stop) to show you where it fails and where smaller sensors do not produce greater dof.

Please consider your same photo example because the same photo with a smaller sensor does not produce a deeper dof with these photos, it produces the same dof. You do not get a deeper dof with a smaller sensor across the full range of focussing distances and _f_-stops. The rule has very real and practical limitations.

But, and it is a big but, it would be true to say that if you were to take the same photo, (same fov, same subject distance), but this time say same dof, then _*the photo on the smaller sensor will always be shot using a wider aperture*_, (except macro of course).

This always has been the advantage of smaller film formats, and still holds true at base ISO. In the samples below I would not get greater dof with a smaller format, but I could take the same photo in the same light at a faster shutter speed and so you can use hand held in a greater variety of situations then you can use the larger formats. I could've taken some of them without a tripod.



Ysarex said:


> "All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."



Only holds true under certain conditions and through a limited range of focus distances and _f_-stops. There is not always a dof difference due to sensor size. Why try an re-invent the wheel and relate things to sensor size when there are perfectly valid principals that do hold true?

Sample photos. The last one was taken with a 55mm lens and is a pano at fixed manual focus, the others an old 35/2 MF lens:


----------



## Tim Tucker (Dec 1, 2016)

robbins.photo said:


> Ok, so for the folks that are arguing the EXTREMELY FINE points here, just stop and ask yourselves, do you honestly think any of this is any way really useful or even understandable to the average photographer in the field? If you really believe that, can you post a simple, one paragraph explanation of why without using any charts, graphs or equations?



See above.


----------



## robbins.photo (Dec 1, 2016)

Tim Tucker said:


> robbins.photo said:
> 
> 
> > Ok, so for the folks that are arguing the EXTREMELY FINE points here, just stop and ask yourselves, do you honestly think any of this is any way really useful or even understandable to the average photographer in the field? If you really believe that, can you post a simple, one paragraph explanation of why without using any charts, graphs or equations?
> ...



Ok, so you want me to follow through all this high end math and you can't even differentiate between 1 paragraph and 6?

Hmm...

Also, nothing in your explanation really tells anyone why any of this incredibly fine hairs your attempting to split matter at all to your average joe photographer.  Can I get the same DOF from a smaller sensor than I can from a larger sensor?  Under the correct conditions, sure.

Do I need 47 pages of charts and graphs to realize this?  Nope.  Do I need a 5 1/2 hour lecture on circle of confusion to understand that... not just no but hell no.

Ok, so maybe we can all just agree that:

1. When someone uses the term bokeh since we all know what they actually meant nobody has to be Mr. Wizard and explain it down to the gnats behind, because frankly it's not really of any use to anyone.  If they are using the term incorrectly, just direct them via weblink for the 450 page dissertation you like best in explaining it and leave it at that. 

2. We can acknowledge that DOF is influenced by several factors and worry about folks that may not understand that gaining a basic understanding of HOW THAT APPLIES IN THE FIELD, rather than every time someone dares use the term bokeh getting dragged into one of these hypertechnical arguments that frankly serve no real purpose.  Lets be honest, they probably confuse most folks far more than help them.


----------



## Tim Tucker (Dec 1, 2016)

robbins.photo said:


> Ok, so you want me to follow through all this high end math and you can't even differentiate between 1 paragraph and 6?



Hmmm...



robbins.photo said:


> Do I need 47 pages of charts and graphs to realize this?



Differentiate between 5 pages and 47? 

As to your general comment, no I do not know how many actually understand it. We may have gone a little deep in places for a beginners forum but there were a lot of basics in there. And though we will check the boring bits you don't wish to see I don't think it fair to criticise us and over-dramatise what was a healthy discussion that may actually  persuade some photographers to learn a little more from other sources.
The space is here, people ask questions and are willing to read, why should there be censure about what they can and can't read if we stay on topic and are civil?

We'll stop now and go back to making comments about popcorn.


----------



## robbins.photo (Dec 1, 2016)

Tim Tucker said:


> robbins.photo said:
> 
> 
> > Ok, so you want me to follow through all this high end math and you can't even differentiate between 1 paragraph and 6?
> ...



Well, slightly more condescending than your normal fair, but I guess no point in feeding into you and the other professors incessant OCD on the topic.

Frankly you've all gone way off the deep end, as you always do, whenever this topic comes up.  I think you realize that, thus the need to obfuscate and scream censorship.  I was just hoping maybe you and some of the others would clue into the fact that when more than a few of the regulars here start questioning the usefulness of what is being posted/argued about that should give you pause to reconsider.

Or I guess you could just leave your professor hat on and continue to lecture to an empty classroom.  Whatever floats your boat I guess.  Have fun posting your charts and arguing moot points for no apparent reason.  

I'm sure there's a veritable flood of people researching the topic in depth even as we speak thanks to the fascinating and scintillating "No your wrong, no your wrong" approach taken thus far.

Still waiting on you to offer a simple explanation as to why any of this would matter to your average photographer, or what benefit it would be to capturing better images.  Lets just say I won't hold my breath.


----------



## pixmedic (Dec 1, 2016)

nice shot


----------



## OGsPhotography (Dec 1, 2016)

I like my Bokeh after a "good" depth of field.


----------



## snowbear (Dec 1, 2016)

I talked to my bokeh about the fifth at Pimlico.  Oh, wait, that's bookie.  Never mind.


----------



## Ysarex (Dec 1, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > Yes, the math requires an accommodation for sensor size. That's all I ever really said: _"Don't forget the size of the recording media. All else held equal to take the same photo with cameras of different sensor size, there will be a DOF difference due to sensor size."_ *You can't do the math and calculate DOF without including the size of the sensor and so sensor size is a factor in determining DOF. When used to take the same photo the smaller format camera will produce deeper DOF.*
> ...



Wrong.
One more time: A comparison makes no sense when you don't compare like objects. (My medium format camera takes photos with deeper DOF than your phone camera. Look here's a photo of the Grand Tetons and it has deeper DOF than your phone camera photo of a bee on a daisy! Proof!) There are two possibilities here for like objects. 1. The same photo. 2. A large average group of average photos. *In either of those two comparisons use of a smaller format camera will produce deeper DOF results all else held equal.* This is common photographic knowledge and has been for a long time:





DOF Master says you're wrong. (Note the CoC value is reduced for the crop sensor camera. Sensor size as such is incorporated into the math calculations.)





Leslie Stroebel says you're wrong. _View Camera Technique _(page 130 5th edition).

The general rule that smaller format cameras produce deeper DOF does not apply only to portrait distances. It applies as a general rule for all distances. Obviously you can take a photo as in the 2nd example below where you have the DOF limits extending across the entire image -- I only needed to turn the APS camera horizontal and re-focus or stop the lens down further to do that. That does not negate the general rule, it simply means there are usage conditions in which it is not critical.

Joe


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## The_Traveler (Dec 1, 2016)

Excuse me, I just got an offer to have a colonoscopy and a root canal simultaneously.both without anesthetic and that sounds better than reading any more of this discussion.


----------



## Ysarex (Dec 1, 2016)

Tim Tucker said:


> But, and it is a big but, it would be true to say that if you were to take the same photo, (same fov, same subject distance), but this time say same dof, then _*the photo on the smaller sensor will always be shot using a wider aperture*_, (except macro of course).



And now you're arguing my position -- glad you agree with me. This is a simple corollary of the general rule that all else equal smaller format cameras produce deeper dof. So of course if you've adjusted a smaller format camera for what you require as sufficient DOF in a specific scene you can take the photo at a lower ISO and/or faster shutter speed than would be possible with a larger format camera which would have to be stopped down further to achieve the *same sufficient DOF to take the same photo.*

And that's a good reason why this general rule is valuable to photographers. That's exactly why my little 1/1.7 sensor compact remains my favorite camera for general walking around -- it's more versatile as the light dims and I don't have a tripod. I'll get sufficient DOF at f/3.2 for a successful photo that just wouldn't work with a larger format.

Joe


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## Tim Tucker (Dec 1, 2016)

robbins.photo said:


> Or I guess you could just leave your professor hat on and continue to lecture to an empty classroom. Whatever floats your boat I guess. Have fun posting your charts and arguing moot points for no apparent reason.





robbins.photo said:


> Still waiting on you to offer a simple explanation as to why any of this would matter to your average photographer, or what benefit it would be to capturing better images. Lets just say I won't hold my breath.



I'm learning to look at things from a different viewpoint. Even though I do not communicate Ysarex's opinion I still read it all and find it interesting and I will question it. I don't see this as OCD, I just like to learn and Ysarex's viewpoint does make me look at things differently even if it doesn't convince me.

I'm sorry you find it boring and can only apologise.




Ysarex said:


> Tim Tucker said:
> 
> 
> > But, and it is a big but, it would be true to say that if you were to take the same photo, (same fov, same subject distance), but this time say same dof, then _*the photo on the smaller sensor will always be shot using a wider aperture*_, (except macro of course).
> ...



I do in part agree with you, it's just that the relationship is not fully reversible because there are some very real limits.



Ysarex said:


> than would be possible with a larger format camera which would have to be stopped down further to achieve the *same sufficient DOF to take the same photo.*



Not in all cases, and not generally true with landscapes. From your own dof calculator (albeit the online version) we have the following which is not an uncommon situation in landscape:






As you can see the difference in dof between the two format sizes is only 5.5ft at the closest distance, and as you are aware the calculator is a guide that does not take into consideration the aberrations or the difference in the rendering of close focus between each lens and thus both can be considered as pretty close to equal. With both lenses set to _f_8 and the subject at 45ft with the closest object at 25ft then there is no difference in dof for the same photo. Further to that, in practical terms my 55/3.5 can focus to _f_16 without showing any softening from diffraction whereas the APS-C systems at 35mm generally exhibit it above _f_11.

(Practical application part), In landscape with my 55mm lens I usually achieve the dof need for the shot. If I can do that then the smaller sensor will not give any increase for the same photo. However with the crop sensor I'm able to do the same at a faster shutter speed and so can shoot while the wind is rustling the trees a little more.

If there are areas in front and behind the dof in the photo then your rule will always hold true. Once the focus point hits the hyper-focal point to infinity the increase in dof from the crop sensor ceases to be proportional to sensor size, once the larger format hits it there is little difference in dof (for the same photo). This is the practical limit and I find this very common in the style of photography that I enjoy. I can also quote text from many books and have posted a link that agrees with my position that Stroebel's rule has very real limitations.

In my own experience I've always found the reverse situation to be the problem. In the above example where the two formats have pretty much the same dof then opening up the lenses produces a change in dof that is not linear or proportional to sensor size. The larger sensor will reduce the dof far faster than the smaller one as Stroebel's rule comes into effect.


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## The_Traveler (Dec 1, 2016)

This is a bit like walking away from a discussion at a New Year's party only to return the next year and find the discussion still going. 

I will return if it gets to page 8.
Or if some big guys with clubs and guns show up at my house and force me.


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## robbins.photo (Dec 1, 2016)

Tim Tucker said:


> I'm learning to look at things from a different viewpoint. Even though I do not communicate Ysarex's opinion I still read it all and find it interesting and I will question it. I don't see this as OCD, I just like to learn and Ysarex's viewpoint does make me look at things differently even if it doesn't convince me.
> 
> I'm sorry you find it boring and can only apologise.



Well, I'll leave you guys to have the exact same argument you've had so many times before when the topic of bokeh comes up.  When your done one upping each other, there's popcorn.

Laters.


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## pixmedic (Dec 1, 2016)

Isn't bokeh that swirly stuff behind the subject?


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## snowbear (Dec 1, 2016)

pixmedic said:


> Isn't bokeh that swirly stuff behind the subject?


Either that or a brand of macha or sushi flavored ice cream.


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## Ysarex (Dec 1, 2016)

Tim Tucker said:


> Ysarex said:
> 
> 
> > Tim Tucker said:
> ...



But generally true for general photography.



Tim Tucker said:


> From your own dof calculator (albeit the online version) we have the following which is not an uncommon situation in landscape:
> 
> View attachment 131050
> 
> ...



This article addresses what's going on when you're near hyperfocal distance: Depth of Field and the Small-Sensor Digital Cameras
_"Note that as the focus distance approaches the hyperfocal distance, DOF increases rapidly. Since this happens for the small-sensor camera with a 31.25mm lens first (because the hyperfocal distance is least), the ratio of the DOF of the small-sensor camera to that of full-frame sensor becomes larger than the ~1.6x that you would get if the lens was focused at a distance much shorter than the hyperfocal distance."_

Like I said earlier "Obviously you can take a photo as in the 2nd example below where you have the DOF limits extending across the entire image -- I only needed to turn the APS camera horizontal and re-focus or stop the lens down further to do that. That does not negate the general rule, it simply means there are usage conditions in which it is not critical."

You like to take studied landscapes in which you commonly have your camera tripod mounted and DOF extending to infinity -- a usage condition which makes this rule not critical. Now take a break for a minute from the landscapes and become a general photographer. Lose the tripod. Photograph the kids in the pool, the dog in the house, friends in the backyard grilling burgers, scenes in the street, a shop window, soccer players in the park, a rose on the fence, a friend with her child, butterflies in the garden, a bottle of scotch, just a little of whatever and everything and sure a couple landscapes (no tripod). And if you heap thousands of such general photos together and compare with another heap of similar photos taken with a different format camera they'll be a DOF variance apparent between the two heaps. It will be due to the change in format.

Smaller format cameras as a general rule take photos with deeper DOF than larger format cameras all things otherwise equal.

Joe


----------



## greybeard (Dec 2, 2016)

My 2 cents.  DoF is really relative to the physical size of the aperture.  If it is small enough you have a pin hole camera and don't really need any lenses at all and everything will be in focus.  The bigger the opening, the shallower the DoF.  When you start relating this opening to focal length and sensor size, things start getting confusing for a lot of people.  This relationship between focal length and aperture opening is called FACTOR or F stop for short.  If the focal length is 50mm and the aperture opening measures 25mm then the aperture is 50/25 or f2.0 but, if the focal length is 200mm and the aperture is 25mm then will be 200/25 or f8.0  But, a 200mm lens at f8.0 will have the same DoF as a 50mm at 2.0.  because the aperture diameter will be the same.   When you change sensor sizes DoF changes again because of the perspective (foreground to background size relationships) differential focal length has to do with sensor size.  For instance a 50mm lens on FF will have the same perspective as a 35mm lens on a crop frame.  Back in the day, they use to etch the DoF scale right on the lens  next to the aperture ring.  On my old FF 35mm I could set my lens to f11, put the infinity mark on (11) and I knew that everything would be in focus from 4ft to infinity would be in focus.  Not quite so easy today.


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## astroNikon (Dec 2, 2016)

pixmedic said:


> Isn't bokeh that swirly stuff behind the subject?


If you want the *real* answer, watch this video


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## petrochemist (Dec 2, 2016)

greybeard said:


> My 2 cents...


Except DOF is proportional to aperture & inversely proportional to focal length SQUARED. The focal length factor does not cancel out.


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## Ysarex (Dec 2, 2016)

greybeard said:


> Back in the day, they use to etch the DoF scale right on the lens  next to the aperture ring.  On my old FF 35mm I could set my lens to f11, put the infinity mark on (11) and I knew that everything would be in focus from 4ft to infinity would be in focus.  Not quite so easy today.



Today those DOF scales are inscribed on all Fuji X system non-zoom lenses -- nice feature.

Joe


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## astroNikon (Dec 2, 2016)

^^^^
Now I'm gonna have to carry around a Fuji lens in my pocket for reference.


----------



## robbins.photo (Dec 2, 2016)

astroNikon said:


> ^^^^
> Now I'm gonna have to carry around a Fuji lens in my pocket for reference.



Don't forget a laser rangefinder to calculate your exact distance to the subject, as well as a super computer do do all this high end computational crap that is apparently required now for every shot.

Or you can do what I do and just  turn the little command dial thingy to stop down the lens a bit more when you just know you need too without any calculus involved.


----------



## Ysarex (Dec 2, 2016)

astroNikon said:


> ^^^^
> Now I'm gonna have to carry around a Fuji lens in my pocket for reference.



Silly. They print paper tables for you.

Joe


----------



## robbins.photo (Dec 2, 2016)

Ysarex said:


> astroNikon said:
> 
> 
> > ^^^^
> ...



Tables that once I gain enough experience to be able to use become more or less obsolete because I already have enough experience to know pretty much what I need without looking it up.

Handy.  But hey, maybe in the future we can skip all this garbage and just post a link to the tables instead.  BAM.  Problem solved.


----------



## Ysarex (Dec 2, 2016)

robbins.photo said:


> Ysarex said:
> 
> 
> > astroNikon said:
> ...



I did that back on page 2 -- problem solved.

Joe


----------



## astroNikon (Dec 2, 2016)

Ysarex said:


> astroNikon said:
> 
> 
> > ^^^^
> ...


----------



## Ysarex (Dec 2, 2016)

astroNikon said:


> Ysarex said:
> 
> 
> > astroNikon said:
> ...



From that photo looks like you need them too. You can download them free off the Internet.


----------



## Tim Tucker (Dec 2, 2016)

Practical application time, this is what I found with APS-C systems.

As you approach the hyper-focal distance to infinity the dof may increase more but once you hit it then the increase in dof slows. The larger format doesn't until it too hits the hyper-focal distance to infinity. When it does and the subject is within the dof range then there is no advantage in dof in the smaller format.
The smaller format however will aways be able to take the shot at a faster shutter speed. However opening the aperture up will not result in reducing the dof much until you get back below the hyper-focal distance to infinity which the larger format will hit first. Therefore the larger format will always have a greater range of dof control for the f-stops available.
This is the problem I found with APS-C and landscapes, not in getting enough dof, but reducing it as in good light with distant vistas because one past the hyper-focal distance to infinity f-stop does not behave in such a linear manner. I really found that it became more like a point-and-shoot with the kit lens.
At certain practical limits the relationships that govern things like dof change and are no longer linear or proportional either within the same camera or between formats. These have a very real practical application and can define the strengths of the various formats and their weaknesses. Trying to invent and force all formats across all ranges to conform to one rule because it's easier to understand can mask why certain formats are more suited to certain styles of photography than others.


----------



## petrochemist (Dec 3, 2016)

Tim Tucker said:


> As you approach the hyper-focal distance ....


The hyper focal distance of course varies with all the same parameters that DOF varies, other than object distance. Yet you seem to be taking it as a fixed distance.


----------



## Ysarex (Dec 3, 2016)

petrochemist said:


> Tim Tucker said:
> 
> 
> > As you approach the hyper-focal distance ....
> ...



I think what he's saying is that, with smaller format cameras, hyperfocal distance is too close to the camera to allow precise control over DOF -- it ramps up too quickly.

Joe


----------



## chuasam (Dec 3, 2016)

DOF is a result of Focal Length, Aperature and Distance to Subject.
Sensor size does not matter. DOF for a 18mm f/1.8 is the same on a micro43 as it is on an 8x10
the view is just a lot larger on a 8x10

You can change bokeh. You can clip on shapes on the front element. Defocus control lenses can also change bokeh.
Bokeh also changes with your aperture.


----------



## Ysarex (Dec 3, 2016)

chuasam said:


> DOF is a result of Focal Length, Aperature and Distance to Subject.
> Sensor size does not matter. DOF for a 18mm f/1.8 is the same on a micro43 as it is on an 8x10
> the view is just a lot larger on a 8x10



Incorrect.





Explanation can be found further back in the thread.

Joe



chuasam said:


> You can change bokeh. You can clip on shapes on the front element. Defocus control lenses can also change bokeh.
> Bokeh also changes with your aperture.


----------



## chuasam (Dec 3, 2016)

Ysarex said:


> chuasam said:
> 
> 
> > DOF is a result of Focal Length, Aperature and Distance to Subject.
> ...


Weird...intuitively it should not change.
Just imagine a lens and the image.
Only thing that changes is the sensor size...why should the DOF change?


----------



## pixmedic (Dec 3, 2016)

chuasam said:


> Ysarex said:
> 
> 
> > chuasam said:
> ...


----------



## snowbear (Dec 3, 2016)

chuasam said:


> Weird...intuitively it should not change.
> Just imagine a lens and the image.
> Only thing that changes is the sensor size...why should the DOF change?


It's that circle of confusion thing.  It's like the speed of light from a moving object being exactly the same speed as light from a stationary object, to the same observer . . . science is jammin' interesting.


----------



## chuasam (Dec 3, 2016)

snowbear said:


> chuasam said:
> 
> 
> > Weird...intuitively it should not change.
> ...


Did you know that light is both a Particle and a wave but not both at the same time.


----------



## snowbear (Dec 3, 2016)

Yep.
I've always referred to physics classes as "Math, with toys."


----------



## Ysarex (Dec 3, 2016)

chuasam said:


> Ysarex said:
> 
> 
> > chuasam said:
> ...



Because DOF is not calculated at the sensor/film. This is a common misconception because if you think about it as a phenomenon that occurs when the image is formed on the film/sensor then, yes, logically you'd think the size of the film/sensor wouldn't matter, it's just focal length, aperture and focus distance. But DOF is defined on the final print and DOF comparisons need to be made comparing like-image prints. When you do that the sensor/film size plays a role. In all the DOF calculations the size used for the circle of confusion is predicated on the sensor/film size and so influences the calculation results.

Joe


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## The_Traveler (Dec 3, 2016)

_*Déjà vu*_


----------



## greybeard (Dec 4, 2016)

And the mass of the ass is relative to angle of the dangle assuming  the heat of the meat remains constant.  In other words, explain this in words the common man can understand.


----------



## Braineack (Dec 4, 2016)

chuasam said:


> Weird...intuitively it should not change.
> Just imagine a lens and the image.
> Only thing that changes is the sensor size...why should the DOF change?



because the f/5.6 aperture is much smaller physically on the micro sensor.


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## chuasam (Dec 4, 2016)

Braineack said:


> chuasam said:
> 
> 
> > Weird...intuitively it should not change.
> ...



No, the f/5.6 refers to the ratio of the focal length to the diameter of the aperture


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## Braineack (Dec 4, 2016)

chuasam said:


> No, the f/5.6 refers to the ratio of the focal length to the diameter of the aperture



whoops, this is what happens when i post before coffee.

This is a weird scenario because the images resulting would be very different from each other.  But the difference in DOF has everything to do with the smaller sensor (COC) size.


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## pixmedic (Dec 4, 2016)

Braineack said:


> chuasam said:
> 
> 
> > No, the f/5.6 refers to the ratio of the focal length to the diameter of the aperture
> ...




oh lord...
here we go, talking about COC size again...


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## Braineack (Dec 5, 2016)

well, it's true.

if you have a small, blurred circle of light on a smaller sensor, it gets magnified greater when viewed in comparison to the same circle of light on a larger sensor.

Think about it the same way longer lenses blur the background more, because you're magnifying the OOF areas into mushy poo.


I think this video does the best job I've ever seen of explaining the "all-things-being-equal" dof question:






start watching at 6:00.


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## astroNikon (Dec 5, 2016)

Braineack said:


> because you're magnifying the OOF areas into mushy poo.


I couldn't find the term "mushy poo" in any of my Hedgecoe books.


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## Braineack (Dec 5, 2016)

clearly it's on page 290:


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## Ysarex (Dec 5, 2016)

Braineack said:


> well, it's true.
> 
> if you have a small, blurred circle of light on a smaller sensor, it gets magnified greater when viewed in comparison to the same circle of light on a larger sensor.
> 
> ...



*Oh Noooooooooooo!!!* He got the DOF part right but he misused the term Bokeh! Quick!! Someone get robbins!!

Joe


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## robbins.photo (Dec 5, 2016)

Ysarex said:


> Braineack said:
> 
> 
> > well, it's true.
> ...



Sorry professor, you folks can continue to one up each other without my help.  Please, continue to beat this incredibly dead horse for another 13 pages with your minute corrections.

If I feel the need, and trust me I won't, I can always refer back to any of the multiple threads in which you folks have had pretty much this exact same conversation dozens of times before.  Nobody learned anything then, and nobody is learning anything now.

So please, by all means, continue to stroke your own egos.  Me, I'm actually just going to go out and shoot some pictures.


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## Ysarex (Dec 5, 2016)

robbins.photo said:


> If I feel the need, and trust me I won't, I can always refer back to any of the multiple threads in which you folks have had pretty much this exact same conversation dozens of times before.



It does come up from time to time. Photography is overrun with amateurs passing around bad info.



robbins.photo said:


> Nobody learned anything then, and nobody is learning anything now.



Now there you're wrong:


 

And I'm happy if just one person learned something in spite of your efforts to derail that.

Joe


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## robbins.photo (Dec 5, 2016)

Ysarex said:


> And I'm happy if just one person learned something in spite of your efforts to derail that.
> 
> Joe



Oh yes professor, it's my mission in life to prevent the new photographer from learning anything at all.  That's why I regularly post.. well, stuff that actually helps as opposed to long winded, esoteric discussions of theory with no practical use.

Hey, my bad.  But then again I stepped away from all this - your the one trying so desperately to draw me back in.  

Sorry, not interested.  Please feel free to continue your worthless ego stroking nonsense without me.


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## pixmedic (Dec 5, 2016)

Did someone mention COC and stroking? 

I'm going back to auto mode.


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## astroNikon (Dec 5, 2016)

pixmedic said:


> Did someone mention COC and stroking?
> 
> I'm going back to auto mode.


That's the only way to get the Picture right, first time.  AUTO mode in all situations.


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## fmw (Dec 7, 2016)

Looks like circle of confusion to me.


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## snowbear (Dec 7, 2016)




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## astroNikon (Dec 7, 2016)

snowbear said:


>


you're being too Mushy Poo


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## Braineack (Dec 7, 2016)

It's a good topic, why delete?

So long as Tony Northrup is out there spew drivel, there needs to be a place where people can actually get truth.


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