Let's get real..exposure? shutter speed? aperture?

Started Sep 24, 2013 | Discussions thread
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tomhongkong Veteran Member • Posts: 3,560
Let's get real..exposure? shutter speed? aperture?

It's fun to read all those posts on exposure and what it means, but let's get back in the land of reality.

Photography has a number of terms which are not literal, but which have come to mean something specific through long use. It is pretty senseless to try to change something which is clearly understood (or should be) by the majority of photographers.

Exposure was originally (I think) just a measure of how long you took the lens cap off your plate camera and literally 'exposed' the emulsion to light. Without a measure of the size of the lens this is a pretty meaningless term so 'exposure' became a composite measure of time and lens 'aperture' and measures the amount of light falling on the emulsion/sensor or whatever. Amount of light ...nothing to do with film speed, sensor equivalent iso, or how the image turns out.

(It actually refers to amount of light per unit of sensor area, as well, thereby removing the misunderstanding that there is more light 'gathered' by an FF camera than an MFT...More total light, maybe, but not in terms of per sensor area)

Aperture is another composite term, properly understood but misused. Aperture implies a linear dimension, but we have used the term for a dimensionless ratio (F number). In reality, the 'aperture', the size of the object lens, does not tell us much without knowing the FL, and converting it to an F number...but we all know what we mean by 'aperture' which becomes an extremely useful measure.

Shutter speed is another. What has the speed of the shutter got to do with anything unless we know how far it travels, and possibly how the closing blade(s) also perform? What we mean is shutter open time, but we all know what we mean by 'shutter speed'

I am sure you can think of other similar terms

Our use of the term, 'Exposure' looks very precise, as long as we keep away from iso (in camera processing)  What next? does 'exposure' include adjustment in LR as well..why distinguish between in camera processing and post processing?

End of rant


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