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Defining correct exposure
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Jun 12, 2018 00:59:09   #
canadaboy (new user)
 
Discounting special effects such as high or low key etc, if asked how I might define correct exposure I could say something like "were it a scene that includes a mid Grey object, correct exposure would be settings that make the object appear as a similar tone in the completed image".

How would you define it?
 
Jun 12, 2018 01:02:23   #
Joe Blow (a regular here)
 
By whatever makes me happy.

Life is not perfect and different days and different locations produce different light levels. I am perfectly content with a subdued room or a very bright beach.
Jun 12, 2018 01:06:20   #
Jesu S (a regular here)
 
canadaboy wrote:
Discounting special effects such as high or low key etc, if asked how I might define correct exposure I could say something like "were it a scene that includes a mid Grey object, correct exposure would be settings that make the object appear as a similar tone in the completed image".

How would you define it?


But what if it does not include a mid grey object? Surely a definition should be comprehensive.
Jun 12, 2018 01:14:10   #
canadaboy (new user)
 
Joe Blow wrote:
By whatever makes me happy.

Life is not perfect and different days and different locations produce different light levels. I am perfectly content with a subdued room or a very bright beach.


That is actually not answering the question.

Of course different locations and circumstances produce different light levels but the question is how do you determine that your chosen settings have resulted in correct exposure for any given light level?
Jun 12, 2018 01:18:11   #
canadaboy (new user)
 
Jesu S wrote:
But what if it does not include a mid grey object? Surely a definition should be comprehensive.


That's my question to you.

What would your definition be?
Jun 12, 2018 01:54:57   #
RichardTaylor (a regular here)
 
canadaboy wrote:
Discounting special effects such as high or low key etc, if asked how I might define correct exposure I could say something like "were it a scene that includes a mid Grey object, correct exposure would be settings that make the object appear as a similar tone in the completed image".

How would you define it?


When the camera has recorded all the light levels in the scene, that it is capable off, at a shutter speed (show or freeze subject and/or camera motion) and aperture value (how much depth of field), with the lowest possible ISO value, that will give me the results I want.

If the camera is not capable of recording all the light values with a single exposure then more than one exposure may be needed to create the final image.

Nowdays I use a live histogram a a guide as to the actual light levels being recordeed.
 
Jun 12, 2018 04:43:01   #
Gene51 (a regular here)
 
canadaboy wrote:
Discounting special effects such as high or low key etc, if asked how I might define correct exposure I could say something like "were it a scene that includes a mid Grey object, correct exposure would be settings that make the object appear as a similar tone in the completed image".

How would you define it?


I'll ask a question back at you. Do you consider this contact print right out of the camera to be a good exposure?


Jun 12, 2018 05:36:24   #
Gene51 (a regular here)
 
Gene51 wrote:
I'll ask a question back at you. Do you consider this contact print right out of the camera to be a good exposure?


If you thought that exposure was terrible, then what would you say about this image?

The point I am making is that a proper exposure is less about how "nice" an image is when you view it on the preview screen or look at the jpeg on your computer screen or print, and has a mid-gray object in it that looks like it does in reality. But more about recording the important parts of the scene, with detail, in such a way that with some manipulation you can extract all of the details, tones and colors to make a complete image. Mnay photographers are proud to state that they do not spend any time manipulating their images. I say that they are "leaving money on the table" by not taking their images and improving contrast, sharpening, dodging and burning, as the photographer who took the picture below did, in order to create a better image. So the first image is a correct exposure, and the ultimate result bears that out.


Jun 12, 2018 05:55:00   #
BebuLamar (a regular here)
 
Gene51 wrote:
If you thought that exposure was terrible, then what would you say about this image?

The point I am making is that a proper exposure is less about how "nice" an image is when you view it on the preview screen or look at the jpeg on your computer screen or print, and has a mid-gray object in it that looks like it does in reality. But more about recording the important parts of the scene, with detail, in such a way that with some manipulation you can extract all of the details, tones and colors to make a complete image. Mnay photographers are proud to state that they do not spend any time manipulating their images. I say that they are "leaving money on the table" by not taking their images and improving contrast, sharpening, dodging and burning, as the photographer who took the picture below did, in order to create a better image. So the first image is a correct exposure, and the ultimate result bears that out.
If you thought that exposure was terrible, then wh... (show quote)


With all due respect Gene, Adams didn't consider that he got the best exposure possible for that image. He would have bracketed but he had time for only one exposure so he had to make the best out of that negative.
Jun 12, 2018 06:06:51   #
warrior
 
Too much gobbly goop!!!
Jun 12, 2018 06:33:30   #
Gene51 (a regular here)
 
BebuLamar wrote:
With all due respect Gene, Adams didn't consider that he got the best exposure possible for that image. He would have bracketed but he had time for only one exposure so he had to make the best out of that negative.


Ah, Bebu, I guess you hadn't read Ansel Adams' own words on this:

"I was at a loss with the subject luminance values, and I confess I was thinking about bracketing several exposures, when I suddenly realized that I knew the luminance of the moon—250 c/ft2. Using the Exposure Formula, I placed this luminance on Zone VII; 60 c/ft2 therefore fell on Zone V, and the exposure with the filter factor o 3x was about 1 second at f/32 with ASA 64 film. I had no idea what the value of the foreground was, but I hoped it barely fell within the exposure scale. Not wanting to take chances, I indicated a water-bath development for the negative."

I interpreted this as nailing the exposure by using a known EV for the moon in the scene, and using his knowledge and experience and the Zone System to ensure a proper exposure. As he said, he was thinking of bracketing but given the circumstances, there was no time.

It's funny how two people can read the same words and come up with a different take. I think he was very precise and knew exactly what he needed to do to make it work. Bracketing was a passing thought until he realized he had a known luminance level he could base his exposure on. But you made it sound like there was a bit of guesswork, and that Adams had some regret that he did not make the best exposure and would rather have relied on bracketing. I'm pretty sure that by the time AA pressed the shutter, he knew he was going to get what he wanted.

Do you have anything that I can read that supports his unhappiness with the exposure, other than the fact he did not have enough time to take a second one?
 
Jun 12, 2018 06:39:36   #
Gene51 (a regular here)
 
warrior wrote:
Too much gobbly goop!!!


Sorry this one has soared over your head. I can assure you, it's not gobbledy goop. There may be some merit for some in discussions like these.
Jun 12, 2018 06:44:56   #
Gene51 (a regular here)
 
canadaboy wrote:
Discounting special effects such as high or low key etc, if asked how I might define correct exposure I could say something like "were it a scene that includes a mid Grey object, correct exposure would be settings that make the object appear as a similar tone in the completed image".

How would you define it?


It is really defined by industry. If you are a fine art photographer or shoot abstracts, you have far more latitude in defining a good exposure - pretty much anything goes. If you routinely submit your work to Reuters, or Sports Illustrated then the image must look really good right out of the camera - not too dark, not too light, and with enough tonality to tell the story. Once the creative director gets his/her hands on it, the minor enhancements to tone, color saturation and exposure will be made. If you shoot products or people in a studio environment for commercial/advertising purposes, your exposures must resemble life. but you have 100% control over lighting to make that happen.
Jun 12, 2018 08:06:56   #
Linda From Maine (a regular here)
 
RichardTaylor wrote:
... that will give me the results I want...
As Richard has said very succinctly, and Gene in a much broader context, there is no universal correct.

What is the correct depth of field, what is the correct focal length, what is the correct angle of view...all, including exposure, are based on the photographer's intent.
canadaboy wrote:
...how do you determine that your chosen settings have resulted in correct exposure for any given light level?
It seems you want to quantify a condition that isn't usually thought of in that way. You use "mid gray" as a reference in your opening, which is certainly valid IMO, but seems limited more to a documentary-style of photography. I am more likely to be attracted to, and shoot for, dramatic lighting. So when the result matches what I saw in my mind for the story I wanted to tell - that's correct.
Jun 12, 2018 08:58:05   #
a6k
 
My suggested answers to a question with many right answers but even more wrong ones:

As Adams suggested when different technology was involved, the best negative is the one that lets you make the best print.

But we are not using negatives and we are not always printing. Of course, in B&W darkroom work the target paper also varied.

So to extrapolate, the best exposure is that which allows you to make the best print or to make the best digitally displayable final image (usually a JPG, of course). In other words, the best final image quality.

I would not use "middle gray/grey" as my standard for this for at least two reasons.
1. In my inept but empirically oriented testing I found that a middle gray (about 18%) target does not result in a value of 128 (where 256 is max). I have learned through reading that other people's cameras don't necessarily work to the same intended result (some assume that the target is 12%, some 18% and so on).
2. For a variety of reasons, the best image quality will usually be obtained at the "right end" of the possible range of exposures, short of "blown". In this concept, image quality includes "noise" as a negative characteristic. An obvious exception might be when stopping down the lens even one stop would sharpen the picture to a greater extent than the consequent loss of quality due to noise.

Of course, my comments assume that the original file is "raw" and with no more compression than the camera insists upon. Just as obviously, then, my comments assume that the photographer will do post exposure processing. I'm also ignoring color balance issues which can affect exposure in ways that are too complex for me to even understand let alone include here. But my bottom line is that middle gray is not even well defined and does not take into account the dynamic range issue. Adams knew that he had gobs of latitude (AKA DR) and also usually had subjects with a large range of reflected light values. Unless our subjects are similar, taking advantage of the modern digital camera's abilities makes a lot of sense.

As a tactic, using a gray card to set exposure, when you know where in the range of possible "densities" it will fall for your camera makes sense. So does "sunny 16" which is just as scientific as the way that Adams set the exposure for the example given earlier in this thread. But I would not say that it's sufficient, only a good starting point.

Anyhow, there's only the intended result and the technique you use to get there. If they are a perfect match then that is the best exposure.
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