Exposure Basics, lesson three?

Started Mar 18, 2013 | Discussions thread
bobn2 Forum Pro • Posts: 59,580
Re: All at once or nothing at all?

richarddd wrote:

bobn2 wrote:

Najinsky wrote:

They believe Exposure has a fixed definition. This is their first error, an error in their foundation on which they are basing everything, and it serves nicely to illustrate the wasted time that can result from a poor foundation.

Well, you should of flagged that languages evolve, like if alot of people use a word as a moniker for some new meaning, that's cool, innit. On the other hand science and engineering depend on precise use of terminology to enable share conceptualisation and communication of the exact. If one allows the rather formal definitions on which that communication depends to be changed by colloquial usage to be less precise, then in the end all that happens is that one has to invent new words or worse, clumsy phrases to recapture the lost precise meanings. The crux of the matter is not the word, but the concept to which the word applies.

I agree, but I think it would be better to say the crux of the matter is understanding how to get the results one wants (or as close to that one wants as is possible). In other words, what are the effects of changing the aperture, shutter speed and ISO dials.

The thing is though, that the difference in conceptualisation changes 'what one wants'. It also changes where one tries to achieve 'what one wants'. As in the old adage 'if I wanted to go there, I wouldn't start from here'.

For example, should I decrease aperture? How will it affect DOF, diffraction, noise, etc.?

If you want to control DOF, ones options are limited for a given scene and perspective. The question then becomes how much you want that DOF in relation to what you're losing for having it.

Those who need to communicate the distinction between "density of light on the sensor" as opposed to "things that affect brightness" shouldn't find it that difficult to find a way to do so, even if "exposure" has become ambiguous. I don't find "density of light on the sensor" all that clumsy - use it once, specify that is what you mean by exposure, and then use the word exposure.

That's a reasonable point of view, but there are many here who would argue even against that, and accuse you of redefining exposure.

I think that is what transpires here. The argument is really not about what 'exposure' means, but about the role of the exposure that happens at capture time in photography. There are those who would like to view the chain from exposure which happens at capture time to exposure which is apparent at viewing time as a black box, with the triad of controls which determine the operation of that black box. They see that those controls affect the exposure which is apparent at viewing time, and they have developed a whole methodology based on that idea which seeks to determine exposure that happens at capture time on the basis of the desired tonality of the output image. On the other hand, there are those who see exposure that happens at capture time as providing the preconditions, on which depend the subsequent steps of providing a viewable image. They see two controls and an environmental factor (unless one brings along a lamp) and they see that the operation of those controls does more than affect the tonal range of the output image. They also see that the subsequent steps provide ample opportunity to control the tonal range of the output image, with more precision and subtlety than an approach based on controlling it by changing the exposure that happens at capture time. They have developed a methodology based on those observations, which seeks to optimise exposure which happens at capture time with respect to factors such as motion blur, DOF and image noise.

I start with a scene. I do some stuff with a camera and then some stuff with LR, PS or other software. I end up with an image.

Various controls on the camera and in the software do various things to the final image. The things I do on the camera relate to the things I do in software, for example, I decrease shutter speed with a view towards moving LR's exposure slider. I try to make it all work to produce the image I want and try not to let technical considerations get in the way of subject, composition and all those artistic considerations.

Is this an unusual approach?

No, I don't think so, but everyone is different. I find myself finding more and more in my shots at the PP stage, when you have more time and better equipment to look at what the shot might be. Then the task of capture becomes more one of maximising the information, so that you can get the most options in PP. I've even had to make myself not frame shots as closely as I used to, because I was finding when I went through in PP, I often wanted to include something I'd cut-off in framing. So all in all, I'm much less about visualising the final shot than I used to be.

So, we have two camps. One whose methodology is based on controlling the exposure that happens at capture time to determine the output tonality of their images, the other whose methodology is based on controlling it to determine DOF, motion blur and image noise. Add to that that many of the first camp take great pride in their advanced skills in 'nailing' exposure to determine the output tonality and that there are few who would like to evangelise their skills and it's hardly surprising that they take offence if someone comes along and tells them that their fundamental understanding is flawed. But it is.

There are jpg shooters who don't post-process

They would seem to go naturally into camp 1.

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