Gerry wrote:
gollywop wrote:
You continue to be in error.
exposure is the amount of light allowed to fall on each area unit of a photographic medium (photographic film or image sensor)
during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value (EV) and scene luminance in a specified region.
The medium is always assumed; what is in question is which factors are in play (and which are not). That question is answered directly with the part that says exposure is defined as:
Hv = Ev .t
where
- Hv is the luminous exposure (usually in lux seconds)
- Ev is the image-plane illuminance (usually in lux)
- t is the exposure time (in seconds)
By any rf defining the meaning of a term in one context can alter - or wipe out ational use of English exposure
time, as opposed to exposure
duration, should mean not how long the exposure was but when it was taken. But, of course, this is pedantry gone mad. Everyone knows that exposure time can have different meanings depending on context. After all, that's true of a lot of expressions.
Indeed, it's true of exposure too. There's nothing wrong with the definition you quote here and it's fine in the context for which it is intended. But, like exposure time, exposure has other meanings depending on context. It isn't an error, as you suggest, to use a term in a different context from the one you happen to prefer.
The logic failure in my title refers to the idea of thinking that exposure can only have one meaning while defining it by reference to a term that can have multiple meanings - if all terms must have just one meaning the definition itself is wrong; or multiple meanings are fine.
