# How do you get the blurry background effect?



## larry909 (Sep 13, 2017)

What do you need in a digital camera to get that effect where you see the object in focus and the background is blurry?
Is it manual aperture and shutter settings? So if a camera has manual aperture and shutter settings it would be able to do that?


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## photo1x1.com (Sep 13, 2017)

Hi and welcome to the forum!
You need to set the aperture. You can do that in aperture priority. How blurry it is going to get depends on a few factors like 

Maximum aperture of your lens (the lower the number the better)
Focal length: the longer the better
Distance background - subject: the further the better
Distance camera - subject: the closer the better
Sensor size of your camera - the bigger the better
If you are interested, I deal with some of the factors in my "effects of aperture" series:


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## jaomul (Sep 13, 2017)

When you focus on something a certain area front and back is very much in focus while the rest starts to get blurred. This effect is more pronounced if you focus on something close and the background is farther away, it is even more pronounced with smaller aperture numbers (larger aperture).

You'll often see portraits taken with an 85mm lens with an aperture of say f1.8 and a lot of background is oof.

Google Depth of field for a more detailed explanation


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## Designer (Sep 13, 2017)

larry909 said:


> So if a camera has manual aperture and shutter settings it would be able to do that?


In short; no.

The list in post #2 above is cumulative in nature.  Only one of those things by itself might not achieve the blur that you want. Do all of those things to maximize the effect. 

Also, it's not just digital.  Film can do it too (substitute "film" for sensor).

Also, not every digital camera is capable of producing the desired amount of blur.  In that list, you really have to maximize all or nearly all of the factors in order to get a blur.  And most of the time the gear (lens, sensor size) doesn't come cheap. 

Also, there is nice smooth blur (sometimes called "bokeh") and then there is jittery, figured blur that is just not pleasant to look at.  The smoothness of the blur is an inherent quality of the lens chosen, and cannot be "adjusted".  It is what it is.


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## Tomasko (Sep 13, 2017)

@Designer , that "jittery, figured blur" is still called "bokeh".


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## Designer (Sep 13, 2017)

Tomasko said:


> @Designer , that "jittery, figured blur" is still called "bokeh".


No, that's the OPPOSITE of "Bokeh".  Bokeh is creamy, dreamy, smooth blur with no figure at all.


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## Tomasko (Sep 13, 2017)

@Designer.

Let's start with wikipedia: Bokeh - Wikipedia
_In photography, bokeh (originally /ˈboʊkɛ/,[1] /ˈboʊkeɪ/ BOH-kay — also sometimes pronounced as /ˈboʊkə/ BOH-kə,[2] Japanese: [boke]) is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens.[3][4][5] Bokeh has been defined as "the way the lens renders out-of-focus points of light"._

photographylife.com: What is Bokeh?
_Basically, bokeh is the quality of out-of-focus or “blurry” parts of the image rendered by a camera lens – it is NOT the blur itself or the amount of blur in the foreground or the background of a subject._

B&H: Understanding Bokeh
_“Bokeh” is an English word that is a translation of the Japanese word “暈け” or “ボケ” that means: blur—specifically out-of-focus blur. So, why not just use the already established word “blur?” Because the simple English word “blur” can be applied to motion blur as well. Also, the word bokeh also encompasses the Japanese word “ボケ味“ meaning “blur quality.” So, bokeh is more than the blur, it is a word used to describe the aesthetic quality of blur._

Nikon: Bokeh for Beginners | Achieving Bokeh in Photographs | Bokeh Effect Tips & Tricks from Nikon from Nikon
_Simply put, bokeh is the pleasing or aesthetic quality of out-of-focus blur in a photograph.

_
So yes, I believe you can talk about bokeh in context of a not really pleasing/jittery/whatever background blur. You wouldn't call it "a pleasing bokeh", but...


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## fmw (Sep 13, 2017)

One correction.  The size of the sensor has nothing to do with depth of field.  It is all about lens focal length and aperture as well as distance.  Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.


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## fmw (Sep 13, 2017)

Designer said:


> Tomasko said:
> 
> 
> > @Designer , that "jittery, figured blur" is still called "bokeh".
> ...



No bokeh is nothing more than the appearance of out of focus areas in a photograph.  Bokeh can be creamy or horrible and you can describe it any way you like since it is subjective.


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## photo1x1.com (Sep 13, 2017)

fmw said:


> One correction.  The size of the sensor has nothing to do with depth of field.  It is all about lens focal length and aperture as well as distance.  Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.


I know what you are referring to, so yes and no. But using the same 85mm lens with the same aperture setting and the same crop of the subject with both full frame and crop sensor would result in a much more blurred background on the full frame image, because you are closer to the subject.


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## Designer (Sep 13, 2017)

Tomasko said:


> So yes, I believe you can talk about bokeh in context of a not really pleasing/jittery/whatever background blur. You wouldn't call it "a pleasing bokeh", but...


Sheesh!  

Whatever.

That would be like calling "rap" music.


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## fmw (Sep 13, 2017)

photo1x1.com said:


> fmw said:
> 
> 
> > One correction.  The size of the sensor has nothing to do with depth of field.  It is all about lens focal length and aperture as well as distance.  Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.
> ...



Lens focal length and aperture.  Subject distance.  Nothing else.  You can use the 85mm lens at any subject distance.  The sensor has nothing to do with it.  You are saying that subject distance affects depth of field and, indeed, it does.


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## TCampbell (Sep 13, 2017)

Bokeh refers to the "quality" of the blur (good or bad).  

Anyway... the three things that go together to produce strong out of focus blur are:

1)  LOW focal ratio adds to the blur
2)  LONG focal length lens adds to the blur
3)  CLOSE subject, distant background (if the background is very close to the subject then the difference in focus between subject and background won't be so strongly different.)

Many lenses are just not capable of producing a very strong blur.  Most DSLR cameras come with a "kit" lens and it's usually something an 18-55mm zoom with a variable focal ratio which can be as wide as f/3.5 at the short focal length (wide angle) end, and f/5.6 at the long focal length (narrow angle) end.  Unfortunately f/5.6 at 55mm will produce very little blur and likewise f/3.5 at 18mm will also produce very little blur.   It's a struggle to get much blur out of these lenses unless you resort to extremes such as putting the subject at closest possible focus distance and putting the background very far away.

It's much easier to do with longer lenses.... 85mm and up and hopefully with a low-ish focal ratio (such as f/2 or lower).   You'll even get a little blur with a 50mm lens and a low focal ratio (f/1.8 or f/1.4, etc.)  but as you get to lower focal lengths it becomes very difficult to produce much in the way of a pleasing blur.  I have a 14mm f/2.8 lens and that lens wants the whole world to be sharp almost no matter what I do.  The most I can do is get enough blur to make it look like I just barely missed focusing accurately (the blur isn't strong enough to look intentional.)

As you get to much longer focal lengths (e.g. 200mm) then you can even get pleasing blur at f/4.  

I have a 135mm f/2 lens which is basically a cream machine (LOADS of background blur) and a 300mm f/2.8 that produces so much blur that diabetics should not look the photos lest they go into insulin shock from all the sweetness!  (Ok, I'm kidding... but just a little).  The point is, LONG lenses with LOW focal ratios produce a LOT of blur when you have a CLOSE foreground subject and a DISTANT background (not close to the subject).

This is 300mm at f/2.8.  In the (distant) background, there is a patio and people are having tea.  







Do you see anyone having tea?  Neither do I.  But since I took the photo, I know that they were there.  This is an example of extreme blur.  Sometimes you don't want so much blur that the background is no longer recognizable.  I have other photos where we specifically wanted soft blur on the background but wanted to make sure you could actually recognize the background subjects for what they were.... in those cases you back away from using the widest possible focal ratio and use something slightly narrower.  

BTW, it is also possible to "fake" the background blur using products such as Photoshop.  

The blur in this background is fake:






Here's the original (as shot):






In the original you can read the wine bottle ... Silver Palm (a very pleasant cabernet).  But this was done for a restaurant who wanted the attention on the food -- and the wine is there to help support the mood.  So we want a bottle (for the mood) and we want you to "recognize" the bottle... we just don't want you to be able to read the bottle.  

To produce this, I had to use Photoshop using masks and layers... the top layer has a photoshop "lens blur" filter applied but the background does not.  There's also a mask to let me selectively reveal the non-blurred plate of food through the "blurred" upper layer and I had to very carefully feather the blur out from around the edge of the plate to create a believable transition.  It took a while to do.

The blur was also done to match the intensity of blur in other shots that were going to be used in the same articles.

So why not just shoot at the same f-stop using the same lens as the other images which had the correct "as shot" blur??

This was the only dish on a wide rectangular plate and composed at an angle.  When I used the same f-stop as the other shots, the food (the main subject) was not entirely in focus the way we wanted.  So we chose to stop down the lens to increase the depth of field, improve the overall look of the food and then "fake" the blur to match the rest of the photos in the shoot.

While I say it is possible to "fake" the blur (with an example), I have seen some really awful fake background blur.  It took me several attempts to try to come up with a fake blur that could pass for natural blur (like all things in photoshop... it's a learning experience. )


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## SquarePeg (Sep 13, 2017)

This is a great subject to experiment with to improve your understanding of dof.  You have 4 main variables:  focal length, aperture, distance from lens to subject and distance of subject to background.  Set up your shot and change one variable at a time to see the effect on your background blur.


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## SquarePeg (Sep 13, 2017)

@TCampbell   gorgeous Iris shot!  They're my favorite. I hope you have that hanging on your wall.


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## vintagesnaps (Sep 13, 2017)

To get that blurry background, open up the lens; but also adjust shutter speed/ISO since you're letting more light into the camera when you use a larger aperture. 

You might need to reread those links Tomasko; the one from B&H says bokeh is more than blur, it's the aesthetic quality of it. The definition from Nikon says it's the pleasing quality of out of focus blur.

Setting up a shot maybe you could for example turn the subject around, or maybe that wouldn't work if there was lettering or other distraction on the other side, but my point is to the OP - look at what's there in the scene and in the background and think about how it's going to look before you release the shutter. Think about your vantage point, you can move and change the perspective and get something different in the frame. 

Depending on the background, even if it's out of focus you could still have shapes or blobs of color or blurred lines and texture that may or may not look good. In the iris example (which is a beautiful photograph) it worked. It doesn't always work that well, it depends.


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## photo1x1.com (Sep 13, 2017)

TCampbell said:


> Bokeh refers to the "quality" of the blur (good or bad).
> 
> Anyway... the three things that go together to produce strong out of focus blur are:
> 
> ...


Awesome iris image, Tim! I love it!


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## Tomasko (Sep 13, 2017)

vintagesnaps said:


> You might need to reread those links Tomasko; the one from B&H says bokeh is more than blur, it's the aesthetic quality of it. The definition from Nikon says it's the pleasing quality of out of focus blur.


I read them, that's why I'm saying bokeh isn't just that "nice smooth background blur" Designer mentioned.


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## Ysarex (Sep 13, 2017)

fmw said:


> photo1x1.com said:
> 
> 
> > fmw said:
> ...



Sensor size is a DOF determinant. We've been through this before, but oh well... If you take the same photo with two different cameras having different size recording media, the photo from the camera with the smaller media (sensor or film) will have more DOF. Wolfgang has this one right.

This is the standard equation for hyperfocal distance: 

 where H = hyperfocal distance, f = lens focal length, N = f/stop and c = circle of confusion. The value for the circle of confusion is in part derived from the size of the sensor. Change the size of the sensor and the value for "c" changes. Change the value for "c" and "H" changes and that's a change in DOF. Therefore, changing sensor size changes DOF.

Joe


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## bianni (Sep 13, 2017)

Why does a bigger sensor lead to a shallower depth of field?


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## Designer (Sep 13, 2017)

vintagesnaps said:


> The definition from Nikon says it's the *pleasing quality* of out of focus blur.


@Tomasko 

I think Nikon might know something about it, considering the concept originated in Japan.  

We can bastardize English 'till the cows come home, but the original Japanese is somewhat protected.  

Unless you want to bastardize the Japanese language as well.


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## Ysarex (Sep 13, 2017)

bianni said:


> Why does a bigger sensor lead to a shallower depth of field?



That's a lot of confused people and wrong answers.

Joe


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## SquarePeg (Sep 13, 2017)

I always was under the impression that the  bokeh can be either pleasing or not.  Bokeh is essentially the blur and we can add descriptors like creamy bokeh, harsh bokeh (that jittery hurts your eyes stuff that the cheaper lenses sometimes produce) and of course my favorite, bubble bokeh!

The Legend And the Bubble Bokeh. Review of the Meyer Optik Goerlitz Trioplan 100mm f/2.8


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## Jamesaz (Sep 13, 2017)

I've always considered bokeh to be the way a lens transmits out of focus specular highlights. I could be way wrong though. It's happened.


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## Tomasko (Sep 14, 2017)

@Designer, seems you didn't read the links. No problem, here are more examples for you once again. I can't believe I have to do this on a dedicated photo forum.

wikipedia
_Differences in lens aberrations and aperture shape cause some lens designs to blur the image in a way that is pleasing to the eye, while others produce blurring that is unpleasant or distracting—"good" and "bad" bokeh, respectively._

bokeh Meaning in the Cambridge English Dictionary (notice the word "NICE" in the eaxmple, as adjectives are almost always used in conjuction with it)
_a blurred (= not clear) effect used in photography:
This lens produces that nice bokeh in the background that looks great in portraits.
_
bokeh | Definition of bokeh in English by Oxford Dictionaries :

The visual quality of the out-of-focus areas of a photographic image, especially as rendered by a particular lens.

_‘a quick, visual survey of the foreground and background bokeh of a variety of lenses’_

_‘Many buy this lens to escape the often poor bokeh of the Vega, but is it really better?’_
_‘Some folks feel the best bokeh has an undefined, blurred edge.’_
_‘For me, the 85 Prime's bokeh just feels easier on the eyes.’_
_‘It is easily light enough for a handheld supertelephoto lens, but what would the bokeh be like?’_
_
_
It's not my definition or anything, this is a standardised term in photography as you can (hopefully) clearly see. It's everywhere defined as the blur and its visual quality, which can be nice/pleasing or bad. I don't know why you're fighting it.


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## fmw (Sep 14, 2017)

Semantics are always hard to debate.


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## petrochemist (Sep 14, 2017)

photo1x1.com said:


> fmw said:
> 
> 
> > One correction.  The size of the sensor has nothing to do with depth of field.  It is all about lens focal length and aperture as well as distance.  Smaller sensor cameras tend to use shorter lenses so that is where this sensor size misconception arises.
> ...


But then you're changing one of the other variables listed. You can use the same lens from the same distance & at the same aperture. The FOV will be different but the DOF won't if the images are viewed in the same way (without cropping etc as printing bigger changes the circle of confusion).


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## Ysarex (Sep 14, 2017)

petrochemist said:


> photo1x1.com said:
> 
> 
> > fmw said:
> ...



You're right that moving the camera invalidates the comparison but so does changing the FOV. *To make a meaningful comparison the two different format cameras must be used to take the same photograph.* Just setting up that "same photograph" comparison can create points for debate, but I think most would agree that the two photos should at least contain identical subject content. Should they both be made at the same exposure setting? Same aperture? When we use formulae to calculate DOF we use standardized variables. Then in taking the "same photograph" we should probably use those same variables -- in that case same f/stop for both photos as opposed to same physical aperture diameter since physical aperture diameter is not a standard DOF formula variable. Furthermore we should work with the industry standardized definition and assessment methods for DOF.

If we do that we arrive at the fact that I believe no one contests: The photo from the smaller format camera will exhibit deeper DOF. That's easy enough to test and prove and it's been done over and over and over.





The fact then that the photo from the smaller format camera has deeper DOF is right there plain to see. The standard industry definition for DOF and the formulae used to calculate DOF are consistent with what the above images show and since we have over 100 years of industry acceptance and reliance on those formulae, I for one vote we continue to use them and rely on them: they're proven. In examining those formulae we find that one of the required variables used in the calculations is a value that is in part predicated on the size of the sensor.





Joe


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## Designer (Sep 14, 2017)

Tomasko said:


> @Designer, seems you didn't read the links. No problem, here are more examples for you once again. I can't believe I have to do this on a dedicated photo forum.
> 
> It's not my definition or anything, this is a standardised term in photography as you can (hopefully) clearly see. It's everywhere defined as the blur and its visual quality, which can be nice/pleasing or bad. I don't know why you're fighting it.


You are not required to keep on bastardizing the English language.  You can cease at any time.

I'm "fighting" for the language.

But heck, let's just see what would happen if I didn't choose to correct your thinking:

Aromatic garbage
Rap "music"
Military intelligence
Congressional action
Ugly bokeh

Considering the source and original meaning of the term; ボケ味_, _we see that there is no equivalent term for "ugly bokeh".  

Just because lazy, ignorant Westerners have bastardized the term by stretching the original definition doesn't mean that the definition has actually changed.  It only means that lazy ignorant Westerners have co-opted the term to mean something that it had not meant previously.  

Yes, of course, I concede that I am vastly outnumbered by lazy, ignorant Westerners, and that common usage of the term now means any kind of blur that you want.  Therefore I yield.


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## SquarePeg (Sep 14, 2017)

*Since we can't seem to play nice and disagree respectfully, let's get back to the topic that the OP was really asking about please.  I don't think someone who needs to ask how to get background blur really gives two shakes about who is right in these other slightly off topic semantic arguments.   *


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## smoke665 (Sep 14, 2017)

larry909 said:


> Is it manual aperture and shutter settings? So if a camera has manual aperture and shutter settings it would be able to do that?



Thank you @SquarePeg for your guidance.  In reading through the posts, I didn't see any followup by the OP. I mean no disrespect to those that responded because they do for the most part know what they're talking about, but I fear the collective flexing of technical muscle might have scared off the OP, as I've seen no follow up by the OP. I don't want to assume the skill level of the OP but based on the wording I would assume limited.

So as a simple answer to the question you posed - Yes you can set your camera to manual and achieve an OOF background. My suggestion is that, if you have a tripod, great if not, try to stay in the same spot. Set the camera to full manual, and take a series of shots adjusting your aperture from about f/8 down to as open as it will go. It's important to maintain the same distance and focus between shots, adjusting the shutter, only to obtain the proper exposure. Once you have this series of shots, you'll have a much better understanding of what all the above posters have been trying to explain.


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## fmw (Sep 14, 2017)

Ysarex said:


> View attachment 146746
> 
> The fact then that the photo from the smaller format camera has deeper DOF is right there plain to see. The standard industry definition for DOF and the formulae used to calculate DOF are consistent with what the above images show and since we have over 100 years of industry acceptance and reliance on those formulae, I for one vote we continue to use them and rely on them: they're proven. In examining those formulae we find that one of the required variables used in the calculations is a value that is in part predicated on the size of the sensor.
> 
> ...



Were the images made at the same focal length?  Obviously the lenses were different.


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## astroNikon (Sep 14, 2017)

larry909 said:


> What do you need in a digital camera to get that effect where you see the object in focus and the background is blurry?
> Is it manual aperture and shutter settings? So if a camera has manual aperture and shutter settings it would be able to do that?


There's a lot of *extreme* detail here.

But to learn about the "blurry" effect it's best to get a 50mm/1.8 lens and start learning about it.  I really did not see any blurry changes with my kit lens.  When I first started using a 50/1.8 then I started seeing the differences in aperture settings.

Here's 3 quick images of different Apertures on the same subject, same distance, etc.   The Blurry effect is much more comparative whn you have a f/1.8 lens or similar.  ==> Struggling with Focus


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## Ysarex (Sep 14, 2017)

fmw said:


> Ysarex said:
> 
> 
> > View attachment 146746
> ...



Of course the lenses were different and the focal length change is of course a factor. The lens change alone however is not sufficient to explain the DOF variation and is not the only factor. In order to run standard DOF formulae that properly calculate what's being seen a value that accounts for the change in sensor size is *required*. No standard DOF calculation is possible that does not include a value for the sensor size. That makes sensor size one of the determinant factors.

Joe


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## Dragster3 (Sep 14, 2017)

No one has really answered the question. 

What do you need to get the desired blur in a DSLR. 

Answer... You need to put it in aperture priority, take a picture the aperture in the lowest #, focus on what you want focused.

Then keep taking the same picture (at least 3 more) with different aperture (higher #)

Then go and download the pictures and pick the one that has the right amount of blur.

If you use a vintage lens or some fancy new ones, look at the scale and it will tell you in meters what is in focus. AKA "Scale"




 

 

Chime in. I think this answers the question about "is rap really music", "is your photograph really art" LMFAO


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## larry909 (Sep 14, 2017)

Thanks everyone for the answers! [emoji2]  Definitely alot of content here to learn more about. interesting to see the debates going on.

@Dragster3
 I wasn't asking about a DSLR here, just a point and shoot, but I guess the same rules still apply.

*

So technically an AF p&s could possibly get a 'pleasing' [emoji6]  bokeh   if in the right condition, but most likely won't?


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## Dragster3 (Sep 14, 2017)

Your question is really not a debate. It's pretty cut and dry. The "scale" is the answer you are looking for.

The scale determines what is in focus. 

I'm the layman.


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## Dragster3 (Sep 14, 2017)

larry909 said:


> Thanks everyone for the answers! [emoji2]  Definitely alot of content here to learn more about. interesting to see the debates going on.
> 
> @Dragster3
> I wasn't asking about a DSLR here, just a point and shoot, but I guess the same rules still apply.
> ...



If the point and shoot has aperture priority, you can do it. Set the aperture number low and shoot away.


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## zombiesniper (Sep 14, 2017)

To answer the OP correctly...........I just don't focus on the background


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## Designer (Sep 14, 2017)

larry909 said:


> So technically an AF p&s could possibly get a 'pleasing' [emoji6]  bokeh   if in the right condition, but most likely won't?


Breaking it down for you; in post #2 there is a list of factors that, if optimized, would produce a blurred background.  

In the average point & shoot camera, the lens is wide, the aperture is small, and the sensor is small.  Those are three strikes against you, but I suppose if conditions were right, you might be able to get some blur.

Get your subject fairly close to your camera, (see zoom comment below) and the background pretty far away.  Try a head-and-shoulders portrait of someone with a distant row of trees in the far-away background.  Set the aperture to its widest setting.  If your lens will zoom, zoom all the way to the longest focal length.  This might force you to back up a bit to get your subject's head all in the shot, but stay as close as you can.  

Try this and let us see how it turned out.


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## larry909 (Sep 14, 2017)

Ok thanks


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## photo1x1.com (Sep 14, 2017)

I don't want to start a new debate, but since to me your post reads rather unpolite, let me tell you that I'm afraid you neither read the question carefully, nor all the answers. 
Here is the OP again:

_What do you need in a digital camera to get that effect where you see the object in focus and the background is blurry?
Is it manual aperture and shutter settings? So if a camera has manual aperture and shutter settings it would be able to do that?_

While your illustration shows one factor for a blurry background, there are a few more that have been mentioned, so I think the question has been answered before.



Dragster3 said:


> No one has really answered the question.
> 
> What do you need to get the desired blur in a DSLR.
> 
> ...


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## rosh4u (Sep 14, 2017)

photo1x1.com said:


> Hi and welcome to the forum!
> You need to set the aperture. You can do that in aperture priority. How blurry it is going to get depends on a few factors like
> 
> Maximum aperture of your lens (the lower the number the better)
> ...


Helpful. Thank you!


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## TCampbell (Sep 15, 2017)

larry909 said:


> Thanks everyone for the answers! [emoji2]  Definitely alot of content here to learn more about. interesting to see the debates going on.
> 
> @Dragster3
> I wasn't asking about a DSLR here, just a point and shoot, but I guess the same rules still apply.
> ...



Correct - Joe (Ysarex) added an equation earlier in this thread that mentioned that sensor size (or film size) is also a factor.  We usually don't think to include that because we're often thinking of changing camera settings or even the lens... but not thinking of changing the camera itself and using a different camera.

Every camera has a "crop factor".  A digital camera with a sensor that is the same size as the negative on a 35mm film camera is typically referred to as a "full frame" camera and has a "crop factor" of 1.0 (we use it as a baseline camera even though there are much larger film and sensors sizes).

Most DSLR cameras have a smaller sensor (the most expensive DSLRs do have "full frame" sensors).  Those smaller sensors are usually the "APS-C" size (named this because it's nearly the same as as a film negative from APS-C film (APS-C = "Advanced Photo System - Classic" size).  Those cameras have a crop-factor of about 1.5 (or a1.6 for Canon).  

The reason I mention this is because if you multiply the focal ratio of your camera by it's crop factor, you'll arrive at the "equivalent" focal ratio w.r.t. how much out of focus blur you'd get with using a full-frame camera.    

An example might make it easier:

That shot I posted with the flowers (Iris) was shot using a "full frame" sensor camera.  But if I had used the same lens with a Canon DSLR that has an APS-C size sensor (1.6 for Canon) then I'd have to multiply my f/2.8 focal ratio by 1.6 to arrive at 4.48 (we'll round that to f/4.5).  In other words if I use a Canon DLSR with an APS-C camera using the same 300mm f/2.8 lens, then I'd get about the same amount of blur that I'd have with a full-frame camera but had stopped down the aperture to f/4.5 instead of shooting f/2.8.  It would be less extreme blur that you saw in the image.

Most point & shoots and smart-phone cameras take this to an extreme because their crop factors are rather large.  Let's pick on Apple...

An Apple iPhone 7 has a camera with an f/2.2 focal ratio (widest possible aperture) and that sounds impressive, but the crop factor is 7.21.

If we multiply 2.2 by 7.21 we get 15.86 (we could round that and just call it "f/16"). 

In other words, every photo taken with an iPhone 7 will resemble what a full-frame camera might get with an equivalent focal length ... but shooting at f/16.    And speaking of focal length... it's a very short lens (remember it's longer lenses that contribute to out-of-focus blur... not shorter lenses).  An iPhone 7 camera is only 4mm (the rear camera).   By the math... it's extremely hard to develop much out of focus blur.

This is why photos taken with smart phones tend to have everything in focus and you never see photos with out-of-focus blur.   Apple knows a lot of people want that out of focus blur, so their iPhone 7 Plus camera (and now the iPhone 8 plus and iPhone X) have two cameras... one takes a focused shot, the other takes a deliberately de-focused shot, and it composites the two images together to create background blur.  It's a bit of a clever trick to do it -- but it would otherwise not be possible at all with such a short focal length lens and such a high focal ratio.


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## Dragster3 (Sep 15, 2017)

Crop factor has always existed... Even in film. Everyone thinks that 35mm is only film that ever existed. LOL

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## Dragster3 (Sep 15, 2017)

photo1x1.com said:


> I don't want to start a new debate, but since to me your post reads rather unpolite, let me tell you that I'm afraid you neither read the question carefully, nor all the answers.
> Here is the OP again:
> 
> _What do you need in a digital camera to get that effect where you see the object in focus and the background is blurry?
> ...


I wasn't being rude. I answered what he needs for the effect and how to get it. I don't want to offend anyone.

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