Exposure control in a raw developer: misnomer?

Started Jan 30, 2013 | Discussions thread
Detail Man
Detail Man Forum Pro • Posts: 16,816
Re: Density of light

Great Bustard wrote:

Joofa wrote:

richarddd wrote:

A goal of someone trying to help photographers understand how to get the best picture quality from their cameras should be to communicate clearly with those photographers. Compare "amount of light on the sensor" (or "density of light" you're so inclined) with "exposure". Which is more likely to get the thought across rather than result in confusion or arguments with most people?

I agree with you. While I can appreciate that people want to introduce technically correct lingo in photography, however, ad hoc terms such as "density of light", etc., without proper qualification, are confusing, in IMHO. I'm not even sure that the proponents of such terms fully understand what they are trying to say.


2: the quantity per unit volume, unit area, or unit length


In common with all types of EMR, visible light is emitted and absorbed in tiny "packets" called photons

Combining the two, we have exposure:


The exposure is the density of light (total light per area -- photons / mm²) that falls on the sensor during the exposure, which is usually expressed as the product of the illuminance of the sensor and the time the shutter is open (lux · seconds, where 1 lux · second = 4.1 billion photons / mm² for green light -- 555 nm). The only factors in the exposure are the scene luminance, t-stop (where the f-ratio is often a good approximation for the t-stop), and the shutter speed (note that neither sensor size nor ISO are factors in exposure).

Seems like there's plenty of "proper qualification" going on, and seems even more clear that the proponents of such terms fully understand what they are trying to say.

Masses (composed of hot gasseous emissions) per unit volume would very likely resonate best here.

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