# iso as an exposure variable - not.



## Patrice (Oct 15, 2010)

Some of the responses in an another thread introduce the control of iso as having an active roll in controlling exposure. 'Exposure triad' is even being bandied about. What a load of s...!

Now that I have your attention, let me explain my point.

I propose that photography is about creating an image with light. I further propose that a 'well exposed image' is an image that conveys the vision of the photographer in terms of mood, content and composition. We don't need to get into discussions about blown highlights or lack of detail in shadows. After all, there is nothing wrong with an 'overexposed' image if that is what the intent of the photographer was.

We have two (not three) controls that have a direct effect on the content and composition of the image: aperture and shutter speed.

We control the depth of field with the aperture and the appearance of motion and the freezing thereof with the shutter speed. Only when we can not achieve or vision with those two controls do we then need to move into controlling the iso. Changing the iso from the camera's base adds nothing compositionally to the image other than adding amp noise. (Unless what we want to create is an image grainy with amp noise.)

When the time comes we can selectively change the iso in different sections of the sensor (think progressive ND filters) then we can start talking about iso having an active roll in exposure, ie: having an active roll compositionally and of an 'exposure triad'.

Changing the iso is the same as loading faster film in the camera. Aperture and Shutter still control the image content. In fact changing film did have a somewhat more active roll than 'sensor sensitivity' in that the different films had very different characteristics in their response to light. Think of the lovely pastels of some Kodak emulsions and the vivid primaries of some Fugi offerings.


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## oldmacman (Oct 15, 2010)

When you popped in a new roll of film, what other dial did you set to let your camera know that you had faster or slower film? ISO is something you control by setting a dial on your camera. The fact that your exposure does indeed change if you forget to alter your ISO reinforces that fact. Many cameras handle higher ISO with ease and only making subtle differences to IQ. This thread seems to be an argument in semantics. When I teach photography I talk about the exposure triangle and point out what changes by altering any of those three settings.


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## Overread (Oct 15, 2010)

I think you're confusing things and presenting a false truth that is going to confuse new people.

Exposure triad is indeed made up of aperture, shutter speed and ISO by considering each of the controllable variables and their own influence on the light that one has to work with. This is excluding ideas of composition and content and purely focusing on the light itself - you cannot deny that ISO is a key part of the exposure just as different speed films were a key part of an exposure in the past.

What you are more talking about isn't just the exposure but the appearance of the exposure itself and there I would somewhat agree that shutter speed and aperture create a major factor in what the final shot will look like. However this is not the same as saying that ISO is not a part of the exposure component. Furthermore its somewhat ignoring the noise factor of ISO as well as the fact that progressively higher ISOs will reduce the dynamic range possible with the camera. 


In addition it somewhat suggests that ISO is outside of the aperture and shutter speeds influence on exposure which is very wrong - a well controlled and exposed shot with a high ISO can look cleaner than an underexposed shot with a lower ISO (this of course within reason)


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## c.cloudwalker (Oct 15, 2010)

Patrice said:


> I propose that ...



You propose whatever you want but it makes no difference. Changing the ISO (whether with a film or digital camera) changes your exposure parameters. Get over it.

The fact that in the film days this could only be done on the fly with some MF and all LF cameras is of no importance. Today, with digital cameras, you can change your ISO as you go. So what? Who cares?

But it does affect your exposure. So, yes, you can say that today ISO is part of the exposure control. And so, yes, you have three (3) controls for your exposure.


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## Garbz (Oct 15, 2010)

This is the biggest load of crap I have ever heard. You can't achieve a desired image with two controls. Suppose you want an image that is tac sharp and has a large depth of field, but it's dark outside. What do you do? Given what you say you have two options:

a) Take the wonderfully composed picture that is 4 stops to high and marvel at your pitch black masterpiece.
b) Cry like a baby because you can't get the photo you desire.


Photography is definitely about creating a picture with light and the sensitivity of you're recording medium is one of the three variables that must be harmonised in order to create the picture you want. Otherwise you're back to the above two options when things go wrong. 

Also if you believe exposure doesn't effect the overall composition of the image I would like to sell you this wonderfully composed picture of a horse:


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## Josh66 (Oct 15, 2010)

Patrice said:


> Some of the responses in an another thread introduce the control of iso as having an active roll in controlling exposure. 'Exposure triad' is even being bandied about. What a load of s...!
> 
> Now that I have your attention, let me explain my point.
> 
> ...


You contradicted yourself in your own post...

Yes, it is all about achieving the photo you envisioned - and ISO is just one tool to help you do that.


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## inTempus (Oct 15, 2010)




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## c.cloudwalker (Oct 15, 2010)

Btw, grain and noise are two different things.

Grain is found in film photography while noise belong to the digital world. And it doesn't look quite the same.


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## Derrel (Oct 15, 2010)

ISO is an exposure variable...in every,single shot made...every morning, afternoon,and night...bracketing via ISO index shifting and push- and pull-processing is a time-honored TRADITION in much commercial photography work where the aperture must remain at a specific f/stop value to control depth of field. Minor 1/3 and 2/3 EV value ISO adjustments are a very time-honored way to get flash exposures that hug to the right hand side of the histogram when shooting in RAW mode. The ISO value in use is a critical,basic part of the exposure equation. It is an essential factor. As in "essential", not optional.

Sorry...nice try...but the premise of this original post is totally,totally "out there" and, uh,  'wrong'...in big ol' air-quotes...


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## manaheim (Oct 15, 2010)

Hey guys, I say let her nail her left foot to the floor.  Why not?  If she would like to think that ISO is not a part of the equation, by all means let her do so.  The rest of us can point and chuckle.

BTW, Patrice, if you're going to go off on a tirade like this you might want to at least know the difference between roll and role.


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## timbearden (Oct 16, 2010)

I can't stop laughing.......ISO being irrelevant?  First I thought someone probably told her that Nikon deals with ISO better than Canon and that she was trying to find a way to reason keeping her Canon.  Then I looked and found out she has a Nikon.   So now, I being totally perplexed, am still laughing.  

I can't wait till she posts a photo using an ISO of 25,600 and it is one big dot, or maybe a couple dots.  Her excuse will be that it was her intent to create a big dot, or a mess of noise.  This is like abstract expressionism to the old masters.  No wait.....pointillism.  At least pointillism actually looks decent.


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## Patrice (Oct 16, 2010)

manaheim said:


> ... you might want to at least know the difference between roll and role.



That was a rather careless piece of post proofreading, sorry. 



manaheim said:


> BTW, Patrice, if you're going to go off on a tirade like this ...



One post does not a tirade make.  (I might go on a crusade and I might shoot a tirade, but it would be difficult to go on a tirade.)

I did not mean to offend anybody and I certainly did not aim my 'tirade' at anybody either.

This seems to have touched a sensitive nerve in some. Thank you oldmanmac, Overread and Derrel for your responses. Your posts provided solid information and supported a considered point of view.

You might also argue that in a broader sense a few other factors have an affect on a photograph viewer's impression of a good exposure. On camera control of white balance, and maybe even more so, the effect of additional lighting and it's modification have a very profound effect on the image. Furthermore, why not include post processing. Critiques to photographic submissions very often advance advice on lighting, aperture, white balance and also shutter speed. However we very seldom see ' ... nice job with your selection of iso, well done!'  

When someone asks about exposure control in shutter priority mode the answer is not only to vary the iso as has been promulgated in some recent threads. To say "... when in tV mode iso controls your exposure" is in my opinion an incomplete answer. Variation of the aperture is very much a valid option, probably more so. 

We are lucky that we can now change the 'film' instantly in our cameras.  The press of few buttons enables us to vary white balance and iso very conveniently. That has not always been the case, once the film was loaded you then only had aperture and shutter speed as 'on camera' controls. Modifying the light and adding filters to the front of the lens were and are still very effective additional means of controlling exposure, albeit with off camera controls. However, within the context of on camera controls, I still believe that the variance of iso away from the sensor's base value is mostly undertaken only when the combination of aperture and shutter speed will not enable us to create the image we want.

(manaheim, I was not aware of an unnoticed sex change  I have fathered four children and it would be a shame for it to all have been a big mistake)


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## prodigy2k7 (Oct 16, 2010)

Patrice said:


> manaheim said:
> 
> 
> > ... you might want to at least know the difference between roll and role.
> ...



Funny, my old film camera has a control for setting the ISO.

And there is a huge difference between white balance, and exposure... :er:


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## shaunly (Oct 16, 2010)

inTempus said:


>



LOL!! ! this made my day:lmao::lmao:


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## altopiet (Oct 16, 2010)

> Funny, my old film camera has a control for setting the ISO.


Yes, and as I remember, you inserted a film with a fixed ASA/ISO value, and could not change that while using that film?


> That has not always been the case, once the film was loaded you then only had aperture and shutter speed as 'on camera' controls


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## timbearden (Oct 16, 2010)

I understand what you are coming at (sorta), however you still have to consider ISO regardless of the presumption.  If you have a camera that can shoot from ISO 100-800, and all have very minimal grain throughout, then doubling the ISO can effect exposure just as the shutter.  With that said, if you are wide open on your aperture, and still need more light, and you already have a long exposure, then ISO remains as the only alternative to increasing the exposure.

Ironically when in terms of exposure, ISO and shutter speed are two things I think of first.  Aperture, as you mentioned not only deals with exposure, but depth of field.  Solely, for purposes of exposure I would look to to ISO and shutter first.  Just because people don't always consider their ISO as often as they should, doesn't mean it has nothing do with exposure or has little importance. 

If you change any one of the three, there will be a change of exposure.

You also mentioned that if one is to change an exposure in shutter priority than one should consider aperture more so.  Why not equally?  If you are shooting a landscape, and you wish everything to be in focus, then changing the aperture would effect that.  That indeed could change the mood of the photo, and the intent you are trying to convey.  With today's cameras, changing the ISO is very beneficial as there will not be a dramatic effect in noise until you get above 1000.  

This conversation probably will end with no one really agreeing, but ultimately ISO is very important to exposure and for someone who might read this thread in the future needs to realize how important it is.  I'm sure Ansel Adams would be rolling in the grave if he thought he didn't have to consider ISO when using the Zone System in figuring out his exposure.  

I digress, tomorrow I'll take photos with my pinhole lens just because the only thing I can do to change the exposure is ISO and shutter. DUN DUN DUN


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## Buckster (Oct 16, 2010)

altopiet said:


> > Funny, my old film camera has a control for setting the ISO.
> 
> 
> Yes, and as I remember, you inserted a film with a fixed ASA/ISO value, and could not change that while using that film?
> ...


Two words: Film backs.

Photographers who wanted that control had it, and could change out film to a different ASA/ISO in the middle of a roll quickly and without a problem using film backs.  They could switch between any number of different films on the fly that way.

Even those shooting without bodies that used interchangeable film backs, especially those using 35mm, often loaded and carried multiple cameras with different film speeds to deal with the need for different ASA/ISO on the fly.

The OP's opening statement is a load of rubbish.


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## inTempus (Oct 16, 2010)

I feel the same way about shutter speed.  Totally pointless to adjust if you're a pro.  The aperture is all that's important.  The little button that illuminates the top LCD is more useful than the shutter.


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## table1349 (Oct 16, 2010)

What a bunch of horse apples! If you are not shooting full time with the sunny 16 rule settings (ISO 100, f16, 1/125th) you are just a piker with a camera.:mrgreen:


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## Overread (Oct 16, 2010)

Patrice said:


> Critiques to photographic submissions very often advance advice on lighting, aperture, white balance and also shutter speed. However we very seldom see ' ... nice job with your selection of iso, well done!'



Generally speaking when people critique they look for an talk about the downsides a little more than the upsides (depending of course upon the photo in question). I've certainly in the past both given a recived comments on the ISO - or in most cases the noise - in a shot. It's a little less seen on websizes because resizing hides a lot of nose so its only on the very high or poor exposures that one tends to see it come to light. 



Patrice said:


> When someone asks about exposure control in shutter priority mode the answer is not only to vary the iso as has been promulgated in some recent threads. To say "... when in tV mode iso controls your exposure" is in my opinion an incomplete answer. Variation of the aperture is very much a valid option, probably more so.



Not sure how this adds any case for or against your argument - beginners make mistakes and sometimes people oversimplify comments when talking to others. You might notice this more on TPF at present as we have a lot of new beginners and comparatively speaking fewer advanced photographers talking. 



Patrice said:


> However, within the context of on camera controls, I still believe that the variance of iso away from the sensor's base value is mostly undertaken only when the combination of aperture and shutter speed will not enable us to create the image we want.



True within limits - I've known people (macro photographers within the areas I look at) who will raise the ISO when shooting. Their aperture is fixed and their shutter speed is fast to ensure no blur and a deep depth of field - whilst flash light further aids to preventing motion blur and also adds to the shots light needs to keep the aperture and shutter speed at the desired levels. However raising the ISO specifically in this case results in less flash light dominating the scene -thus meaning that more natural light is allowed to take dominance.
This thus reduces the black/dark backgrounds that often come with macro photography where flash is the dominant light source.

I am sure there are other situations where a specific raising of the ISO is a desired effect that the photographer wants. 


However it still does not diminish the fact that the ISO is still playing a key part in the exposure.


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## Derrel (Oct 16, 2010)

Shifting the ISO is really pretty useful in a lot of flash photography situations, especially when your flash units are "maxed out", but you still want more exposure. A couple months ago a friend asked me to come over and help him with a small product shoot, and we did a pretty fair amount of exposure bracketing using the camera's ISO control.

ANother place where ISO value adjustment can be handy is when using a flash that is NOT connected to the camera directly; it is possible to use the flash's ISO setting to deliberately cause, typically, under-exposure for fill-in flash, by deliberately setting the flash unit's ISO control one,two, or even almost three f/stops HIGHER; in this way, deliberate mis-setting of the flash unit's ISO control will cause the flash to output less light than it normally would if the ISO value in use in the camera had been entered correctly. THis mighty seem rather old-school,and it is, but it's the way many people shot fill-in flash photos back in the day using the semi-automatic flash units of the 1970's and 1980's; the camera would be loaded with color film of ISO 100 speed; the flash unit could be set with its ISO value deliberately set to around ISO 640, thus providing fill-in flash that was two and two-thirds EV value dimmer than the exposure of the main,daylight exposure.

I know this second example is not quite what the OP was about, but it does point to an actual method of using the ISO Value setting of photographic equipment as a way to "regulate" exposure.


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## bentcountershaft (Oct 16, 2010)

If I'm shooting a concert with a lot of variance in lighting the ISO is generally the only thing I adjust through the night once I had a shutter speed and aperture I'm happy with.  Same thing with out door shots with varying cloud cover.


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## Hardrock (Oct 16, 2010)

Have to totally disagree with the op, ISO is an exposure variable for sure. In order to get F2.8 with 1/400th of a sec at a nighttime football game you have to adjust ISO accordingly.  I never had the luxury of buying film but Im sure the people who did would ask for a certain film ie: 100,200,800 for what they were shooting.  Im sure they just didnt go to the store and take what ever the person behind the counter gave them. So Im not totally sure what the op is trying to say?!?


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## Derrel (Oct 16, 2010)

I hate to appear to be piling on, but Nikon and Pentax both have very advanced exposure control systems that feature an AUTO ISO. Nikon has a feature called AUTO ISO in wide deployment...it shifts the ISO values up or down as  away to maintain a desired exposure setting baseline that the user selects...or to get 'the right exposure' by wildly shifting the ISO used in extreme situations that are far, far outside the normal.

Nikon auto-iso is extremely useful | Community Matters

Nikon D3 / D300 Vs. Canon
"Possibly the most advantageous feature for me that the Nikon D300 and D3 have, and most current Canon models do not, is auto ISO capability. The way Nikon implements it is to allow the user to set the lowest ISO that he or she wishes to use, and also the highest. The lowest shutter speed for the camera to automatically use also may be preset.

From then on the camera, whether set to Aperture Priority, Manual, or full Program mode,the camera will adjust the exposure parameters as usual, but, when the light level falls so low that the camera's minimum lens aperture is reached, and the shutter speed is as low as you have set it to go, the camera will then automatically increase the ISO as much as needed to fall within these parameters. The ISO being set is always visible on the top LCD as well as in the viewfinder.

Here's an example of the power of this feature. Imagine that you're walking down the street on a sunny day photographing people in the shade as well as bright sun. The camera is set to ISO 200, an appropriate sensitivity setting for the situation.

All of sudden you look into the dark doorway of a building and see something worth photography. Maybe it's a simple still life tableau, or possible a murder under way, (Pulitzer prize here I come). With the Nikon you simply frame and shoot. If the camera needs to run the ISO up to 1600 or 6400, whatever is needed to give a usable exposure, you've got the shot. With the Canon and no auto-ISO, you need to take the time to judge what ISO setting might be required, to set it, and then to take the shot. Auto ISO is available on both the D300 and D3."


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## RSPhotography (Oct 16, 2010)

When you shoot with film you make a decision on what ISO film you use. If you're shooting at a concert where you know it will be dark you choose a faster film.

Just because you make the decision early on, doesn't mean that it's not an important part.

The fact you can do it 'on the fly' with a digital SLR is just a convenience.


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## edouble (Oct 16, 2010)

Derrel said:


> I hate to appear to be piling on, but Nikon and Pentax both have very advanced exposure control systems that feature an AUTO ISO. Nikon has a feature called AUTO ISO in wide deployment...it shifts the ISO values up or down as  away to maintain a desired exposure setting baseline that the user selects...or to get 'the right exposure' by wildly shifting the ISO used in extreme situations that are far, far outside the normal.
> 
> Nikon auto-iso is extremely useful | Community Matters
> 
> ...



My D5000 has auto ISO but I never use it. Like you explained set the parameters for the auto ISO to use and shoot. I prefer to make these decisions myself.

I agree that ISO is just as important as aperture and shutter speed but to a degree I understand the op position. Like Ansel Adams said (not a direct quote) everybody has a viewpoint and it is the responsibility of others to disprove/approve it. I believe Ansel Adams and his colleagues already disproved the op position.


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## Christie Photo (Oct 16, 2010)

Not to open a whole new can of worms...  (OK. Yes.  New can.)

Don't ISO, ASA, DIN...  well, don't they ALL refer to EI...  that is, EXPOSURE index?

-Pete


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## Derrel (Oct 16, 2010)

Pentax has an interesting option called TAv mode...here's a web page that shows a picture of this mode on the top deck mode dial, along with another exposure mode called Sv or Sensitivity Priority.

In TAV mode, the users selects a FIXED shutter speed and a fixed aperture, and then the camera computes the exposure by adjusting the ISO values upward or downward.

Pentax K10D Review: 5. Operation & Controls: Digital Photography Review


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## Helen B (Oct 16, 2010)

Christie Photo said:


> Not to open a whole new can of worms...  (OK. Yes.  New can.)
> 
> Don't ISO, ASA, DIN...  well, don't they ALL refer to EI...  that is, EXPOSURE index?
> 
> -Pete



Yes, indeed. ISO only equals EI when certain conditions are met. Strictly speaking a film only has one ISO (though B&W films can have ISOs varying over a small range, because the developer used in the ISO test is no longer specified but may be chosen by the tester). Everything else is an EI. As an aside, motion picture colour negative films don't have any ISO speed, because there is no relevant ISO standard - they only have EIs.

Best,
Helen


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## shaunly (Oct 16, 2010)

Derrel said:


> Pentax has an interesting option called TAv mode...here's a web page that shows a picture of this mode on the top deck mode dial, along with another exposure mode called Sv or Sensitivity Priority.
> 
> In TAV mode, the users selects a FIXED shutter speed and a fixed aperture, and then the camera computes the exposure by adjusting the ISO values upward or downward.
> 
> Pentax K10D Review: 5. Operation & Controls: Digital Photography Review



Nikon has that mode too. Just put it on M then set your shutter speed and f-stop. Then Auto ISO will do the rest.


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## Patrice (Oct 16, 2010)

This getting to be a bit of fun. Lots of participants thinking about the my statements and countering with well considered arguments. (Some are also just saying I've lost my marbles, but not really contributing.)

Let me say my piece in another way, if you will.

The camera creates an image by exposing the sensor to light. Aperture and shutter are the controls that vary the amount of light that can reach that sensor. I fully acknowledge that changing the response parameters of that sensor to the amount light it receives will entail changes in one or both of the two controls I'm talking about. Changing the iso does not vary the amount of light the sensor receives, only its response to that light.

An image requiring a large depth of field and a fast shutter speed certainly might necessitate a higher iso due to the lack of available light. 
So we raise the iso so that we can use the aperture and shutter speed the image requires. We are still only using aperture and shutter speed to control the amount of light reaching the sensor.

Of course changing the iso will require a change in aperture and/or shutter speed to maintain the same exposure. But it's not the change in iso that is modifying the exposure, it's the resultant changes in shutter and/or aperture.

I'm gonna shut up now and go eat my supper.


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## Overread (Oct 16, 2010)

So what you're really talking about isn't making an exposure but about light control within the photographic setup. At which point you're assuming that the photographer is working only with natural lighting. Otherwise its not just aperture and shutter (and I'll say ISO as well because the ability of the recording medium to react to light IS a part of the process - it has to be otherwise the concept of low or strong light is meaningless) but also the light controling elements as well - flash, diffusers, black screens, lens hoods, filters, reflectors etc... all come into play with light control and manipulation. 

But this is moving away from the bare bones - the bare bones is you have a recording medium - film, sensor - which reacts to light. Changing how it reacts to light is just as big a part of making an exposure as changing the amount of light it has to work with.


darn it she types faster than me!


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## Patrice (Oct 16, 2010)

erose86 said:


> Unless I am mis-reading your new post entirely (and someone please correct me if I am), I still say your claim is incorrect.
> 
> Enjoy your supper.  :sillysmi:



You are not misreading my post. You said the same thing. If you don't have enough light for the aperture and shutter you want to use then you have to amplify the sensor output. You have not changed the amount of light at all. You can only do that with aperture and shutter.


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## Overread (Oct 16, 2010)

Patrice said:


> erose86 said:
> 
> 
> > Unless I am mis-reading your new post entirely (and someone please correct me if I am), I still say your claim is incorrect.
> ...



But you have to factor in the ISO because otherwise the light that the aperture and shutter speed are affecting has no meaning. What is strong or weak light? Your recording medium defines it of course and be it film or a sensor that recording medium can vary its reaction to the light. This ability to vary its reaction is what makes it part of the exposure triangle. I agree if film/ISO were always  a fixed value it wouldn't matter in the triangle because with no variation you would have no choice. But we do have the variation and be it with film or a digital sensor we can change that value and thus it becomes part of that triangle of camera settings that affects the resulting exposure we get.


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## Josh66 (Oct 16, 2010)

Patrice said:


> erose86 said:
> 
> 
> > Unless I am mis-reading your new post entirely (and someone please correct me if I am), I still say your claim is incorrect.
> ...


You can only do that by adding more light.

Aperture and shutter speed don't change the light either...


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## Patrice (Oct 16, 2010)

O|||||||O said:


> Aperture and shutter speed don't change the light either...



.... only how much of it reaches the sensor.


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## Josh66 (Oct 16, 2010)

Patrice said:


> O|||||||O said:
> 
> 
> > Aperture and shutter speed don't change the light either...
> ...


How is that different than changing the ISO?


No matter what settings you choose, the light is the same - all you can change is how you record it.


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## Destin (Oct 16, 2010)

altopiet said:


> > Funny, my old film camera has a control for setting the ISO.
> 
> 
> Yes, and as I remember, you inserted a film with a fixed ASA/ISO value, and could not change that while using that film?
> ...



But, pushing the film speed by telling the camera it was a different speed than it actually is, was also a viable option in certain situations in the film days. So you could argue that you has iso control on film cameras, albeit in a different sense


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## white (Oct 16, 2010)

Of course ISO has a "direct effect" on the content of an image. Portrait shooters in the 19th century had to ask their subjects to remain still for the duration of the photograph because the speed of emulsions at the time were so slow. Forget about getting crisp shots of moving objects at that time. 

More recently, if 25 iso is all you got in the back of your camera, but you want to stop motion, is it going to happen? No, not even at the widest aperture.

ISO is a controllable feature that allows different aperture/shutter combinations to be used. It is the foundation on which a house is built. It is the recording medium. How much more of a "direct effect" can one ask for?


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## Aayria (Oct 16, 2010)

Guess it's time to tell Canon and Nikon that their "jig is up" so to speak... They've been making a fortune producing cameras that can perform at higher and higher ISO's than ever.. 

But now photographers know the truth.  ISO is all a ruse... No point in paying the extra funds for great ISO performance.  Just give us fast glass, good FPS with high shutter speeds, and darn the ISO performance to heck. "Real" photographers don't rely on such piddly superficial nuances anyway.


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## Aayria (Oct 16, 2010)

I was going to type the "hugging" smiley emote back.. but after the weekend we've had here.. I think this is far more appropriate!

:cheers:

And on that note, enjoy the debate, I'm cracking open some wine with the hubby and calling it a night!


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## timbearden (Oct 16, 2010)

Aayria said:


> Guess it's time to tell Canon and Nikon that their "jig is up" so to speak... They've been making a fortune producing cameras that can perform at higher and higher ISO's than ever..
> 
> But now photographers know the truth.  ISO is all a ruse... No point in paying the extra funds for great ISO performance.  Just give us fast glass, good FPS with high shutter speeds, and darn the ISO performance to heck. "Real" photographers don't rely on such piddly superficial nuances anyway.



Hit it on the nose.  I need to return all my equipment, as I can go to cheaper cameras who don't emphasize ISO.  

I guess the new Ektar film that claims to have less grain at the same ISO is worthless to.  Probably just digital silver anyway.


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## Shane Anderson (Oct 20, 2010)

Your view is very sensor-centric.  A camera is more than just the sensor, and an image is more than just the light hitting the sensor.

Tell me, how do you judge correct exposure?  Isn't it a judgement of whether the *image* has too much or too little light?  And doesn't that judgement use as two of its parameters whether there is lost shadow detail or blown highlights?  And aren't those limits set by the sensitivity of the sensing medium, be it a photoelectric sensor in a digital camera or film in a film camera?


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## Rekd (Oct 20, 2010)

Patrice said:


> Blah blah blah, me me me....



I have a ham sammich.


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## Christie Photo (Oct 20, 2010)

Shane Anderson said:


> Tell me, how do you judge correct exposure?



Well...  everything relates back to 18% reflectance (or 12% luminance, depending on which school of thought you accept).  That's the benchmark.

-Pete


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## ironsidephoto (Oct 25, 2010)

I love that white balance was introduced into this a while back...like it has anything to do with exposure at all. 

Make that a triple face palm. Hah.

I agree with an early poster--as long as the OP doesn't keep spreading rubbish and harming the work of other photogs, let him keep on keepin' on and keep making unsatisfactory images because he doesn't understand the value in 1/3 of his primary tools.


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## Shane Anderson (Oct 25, 2010)

Christie Photo said:


> Shane Anderson said:
> 
> 
> > Tell me, how do you judge correct exposure?
> ...


 
I'm pretty new at this but you're talking white balance, not exposure.


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## Neil S. (Oct 25, 2010)

Derrel said:


> ISO is an exposure variable...in every,single shot made...every morning, afternoon,and night...bracketing via ISO index shifting and push- and pull-processing is a time-honored TRADITION in much commercial photography work where the aperture must remain at a specific f/stop value to control depth of field. Minor 1/3 and 2/3 EV value ISO adjustments are a very time-honored way to get flash exposures that hug to the right hand side of the histogram when shooting in RAW mode. The ISO value in use is a critical,basic part of the exposure equation. It is an essential factor. As in "essential", not optional.
> 
> Sorry...nice try...but the premise of this original post is totally,totally "out there" and, uh, 'wrong'...in big ol' air-quotes...


 
+1

Clearly Iso is one of the major factors that control exposure for digital photography.

Auto-Iso even allows the camera to scale it as needed, providing an additional means to ensure proper exposure.

The way that Iso affects exposure is really no different than that of shutter and aperture, they all control the amount of light that the sensor records in some way.

The main difference is that while shutter and aperture actually reduce or increase the incoming light, the Iso setting simply boosts the sensors ability to gather light at the cost of increased noise.


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## Dao (Oct 25, 2010)

Shane Anderson said:


> Christie Photo said:
> 
> 
> > Shane Anderson said:
> ...




Quote from B&H "Introduction to Light Meters"


"Reflected measurements would indicate different exposures for each  object. Incident measurements would indicate the same exposure for each  object, to render a consistent exposure. Light meters are calibrated to  assume that all subjects are of average 18% reflectance, or neutral  gray. *The use of the 18% neutral gray standard allows a reflected light  meter to render correct readings for &#8220;average&#8221; subjects in &#8220;average&#8221;  lighting situations.* (The value of 18% neutral gray is also referred to  as Zone V in the Zone System, an advanced black and white exposure  method.)"


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## ghpham (Oct 26, 2010)

Dao said:


> Shane Anderson said:
> 
> 
> > Christie Photo said:
> ...


 

That doesn't really tell you anything.  There is no such thing as a "correct" exposure.  There are some general acceptance as to what a "pleasing" exposure should look like, but as an artist, you should feel free to achieve any exposure you want (other people may react unfavorably).


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## Shane Anderson (Oct 26, 2010)

Dao said:


> Quote from B&H "Introduction to Light Meters"
> 
> 
> "Reflected measurements would indicate different exposures for each  object. Incident measurements would indicate the same exposure for each  object, to render a consistent exposure. Light meters are calibrated to  assume that all subjects are of average 18% reflectance, or neutral  gray. *The use of the 18% neutral gray standard allows a reflected light  meter to render correct readings for average subjects in average  lighting situations.* (The value of 18% neutral gray is also referred to  as Zone V in the Zone System, an advanced black and white exposure  method.)"



So if I shoot a gray card then it will fix my exposure and stop my highlights from blowing out?


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## white (Oct 26, 2010)

Some scenes have a range of tones that exceed what film or digital is capable of recording. It's called dynamic range. Don't waste your money on gray cards. Shoot your hand, or the grass, or whatever. It's all pretty much middle gray.


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## Dao (Oct 26, 2010)

ghpham said:


> Dao said:
> 
> 
> > Shane Anderson said:
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Did you noticed that the other poster thought the gray card was for white balance only so I point out it is for exposure as well?


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## Dao (Oct 26, 2010)

Shane Anderson said:


> Dao said:
> 
> 
> > Quote from B&H "Introduction to Light Meters"
> ...




It depends on the particular situation and what you want to accomplish.  If you ran into situation like blown out highlight, create a new thread with the sample photos and tell us what you want to achieve,  we may be able to give you some opinion on that.


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## timethief (Oct 26, 2010)

any change in any one of the 3 elements (AP/SH/ISO) will cause a predictable impact on the other and consequently  impact the final image.


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## Christie Photo (Oct 26, 2010)

Shane Anderson said:


> Christie Photo said:
> 
> 
> > Shane Anderson said:
> ...



Yeah... you are new at this.

A grey card reflects approximately 18% of the light that falls onto it.  And yes...  it is also considered to be neutral in color and can be used for white balance.

I want to re-emphasise the word "benchmark."  A benchmark is an anchor used as a point to which everything else relates.

Think about the room you are in right now.  Is it too warm?  Too cool?  To answer this question, we first need something to which we can relate.  I suspect if you want to store ice cream, the room is too warm.  Similarly, if you want to incubate eggs, I suspect the room is too cool.

For quite some time now, the benchmark used in photography is 18% reflectance.  So if we find our developer is too warm, we mean it's too warm to achieve a negative to produce 18% gray.  Or if the development time is too short, it means too short to achieve 18% gray.  It's the same with exposure.  Simply put, the meter in your camera is telling you how to achieve 18% gray.  So if you put a grey card into a scene you want to photograph and read the light reflecting off the card, you will have proper exposure for that light.

Of course, this is a very simple, general way of thinking about the process.  But it will get you very close.  There are other factors that will come into play that you will learn with experience, such as angle of reflectance.

ISO too relates back to 18% reflectance.

Since I began working with digital imaging, I favor an exposure that's just a bit under 18%.  This is where personal style and desired results come in.

I hope this helps.

-Pete


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