Exposure Basics, lesson three?

Started Mar 18, 2013 | Discussions thread
Dennis Forum Pro • Posts: 17,976
Re: All at once or nothing at all?

As you say, learning is a step by step process. Building foundations, then building on those.

Some people, especially if they are very smart, seem to think learning should be a brain dump, ideally via a plug-in cable with a little flashy 'uploading' symbol the show progress and an alert to indicate the process is finished. Very few of these people become good educators.

I'm not convinced that teaching exposure triangle, based on outdated concepts, first, then trying to undo that to teach what's really happening and why it's important, is sensible.  Witness the endless confusion when we try to explain these concepts to people who have already learned exposure triangle.

A few smart people take objection to including ISO, but they are wrong (in this context) and are not used to being wrong and not handling it too well.

Saying that smart people are wrong doesn't make you smarter or less wrong.

They believe Exposure has a fixed definition. This is their first error, ...even when limited to the photographic context, there are still multiple usages of the term, and phrases based upon. And this is the crux of the 'discussion'. Here are the two key ones in simplified form.

"They" claim there's one; you claim there's many ... you're not right just because you claim to be right.  Most of your counterexamples (double exposure, etc) have nothing to do with the issue at hand, which is simply: does exposure mean the amount of light to which you expose the sensor ?  Or does it mean some indication of final image brightness derived from the amount of light to which you expose the sensor combined with some post-capture data manipulation to change the brightness ?  I claim it's the former; I understand that many use the latter, and I think that how you use it isn't so important as whether you understand the distinction.  If you're aware of the issues, call it Fred if you want.

For film/JPEG/TIFF shooters, the term 'Exposure Triangle' has to include the three components of Aperture, Shutter and ASA/ISO in order that the photographer can control the appearance of their recordings to their liking.

Sure, that and you can't have a triangle with only two sides.  Nobody ever said you get to ignore ISO.

| This is the correct foundation for beginners where the overwhelming majority of cameras and photographers shoot JPEG.

I disagree.  I think it's difficult to unlearn that in order to understand the lack of importance that ISO has.

What has happened with digital, is the film has been replaced by the sensor and varying ISO implemented via electronics trickery (amplification).

I'm under the impression that amplification is not done any more; that ISO is simply data manipulation, adding credence to the idea that it has nothing to do with exposure.

The problem with the "exposure triangle" is that it teaches that ISO is responsible for noise (and low dynamic range).  It creates an artificial emphasis on ISO, leading people to think in terms of ISO when they shoot.  Instead, if they understand that their aesthetic *and* technical image quality comes from their choices of shutter speed and aperture, and ISO is just the final processing done to brighten the image if necessary, they'll learn to choose their exposure settings in an optimal way.

- Dennis

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