define "exposure"

Started Sep 1, 2017 | Discussions thread
ThrillaMozilla Veteran Member • Posts: 3,118
Re: define "exposure"

bobn2 wrote:

ThrillaMozilla wrote:

What a mess. The literature is absolutely bonkers.

For example, the Wikipedia article defines EV in terms of camera settings (exposure time and f stop), but then uses it to express subject luminence.

Subject luminance is strictly EV₁₀₀, subject luminance expressed as that luminance that provides nominal exposure with the given EV and 100 ISO'. Unfortunately, it is common to omit the '100' suffix, which causes much confusion.

I see. Well, in Table 1 the Wikipedia article could do that, or it could specifically refer to subject luminance in EV. But it doesn't. Furthermore, it should put all the definitions of the term in one place, and not hide one term. But it doesn't do that.

But there's more. I looked up photographic exposure in Wikipedia. It states: "In photography, exposure is the amount of light per unit area (the image plane illuminance times the exposure time) reaching a photographic film or electronic image sensor, as determined by shutter speed, lens aperture and scene luminance." Right beside that statement is a caption that states: "Diagram shows the relationship between aperture, shutter speed, and film speed, the three elements in photography that make up exposure." (Emphasis added.)

Contradictions like this are not limited to Wikipedia. The competing definition is found all over the literature, or at least all over the Web. Any term loses its usefulness when conflicting definitions gain widespread use. Gentlemen, there is a problem.

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