Hmm. Or another way of putting it: the first four determine what exposure you get; the fifth determines which of the possible exposures is correct. More or less what you said, but looking at it from the other side. More useful/less useful?
"Fortunately, it's usually a fairly simple 2-1 ratio [...]"
*nod* I've always seen reciprocity explained just in terms of shutter speed vs. aperture, but it really works all the way around: trading ISO against shutter speed instead of aperture against shutter speed, for example ... or moving lights closer or farther away from the subject. Thing is, even with all the variables, the relationships remain simple.
I wonder whether some folks are intimidated by the numbers (especially multiples-of-√2 f-stop numbers), not realizing that most of the time they won't be thinking in terms of specific numbers, but in terms of "one more stop", "two stops less", etc. from some meter-determined starting place.
"[...] it was a common practice to bracket a shot [...]"
I don't know how common it is now, but I do know that's one of the things my new camera automates even though digital seems more tolerant of over/under exposure than slide film. (It even lets me choose whether I want the order to be 0/+/- or -/0/+.) So I'm pretty sure the practice hasn't died out. I find it useful when I'm in a hurry -- when I want to concentrate more on composing quickly and tracking a moving subject than thinking about the exposure, and I know I'm in a fool-the-meter situation. (Another trick I use is a really lazy approach to 'zone' thinking: switch to spot-meter mode, pick different spots to meter on, use exposure-lock when I recompose, and pick the version I like best in editing later.)
And of course when shooting IR film, where the meter only gives a vague, unreliable idea of how much IR light there is in the scene, I bracket very widely. (I need to get a #89 or #87 filter and experiment with shooting IR in the DSLR. Instant feedback should mean not needing to bracket as much, because I should be able to get an idea how far to compensate from what the meter says that day.)
My only problem with auto-bracketing is when I forget to turn it off again after I'm done with it.
(no subject)
"Fortunately, it's usually a fairly simple 2-1 ratio [...]"
*nod* I've always seen reciprocity explained just in terms of shutter speed vs. aperture, but it really works all the way around: trading ISO against shutter speed instead of aperture against shutter speed, for example ... or moving lights closer or farther away from the subject. Thing is, even with all the variables, the relationships remain simple.
I wonder whether some folks are intimidated by the numbers (especially multiples-of-√2 f-stop numbers), not realizing that most of the time they won't be thinking in terms of specific numbers, but in terms of "one more stop", "two stops less", etc. from some meter-determined starting place.
"[...] it was a common practice to bracket a shot [...]"
I don't know how common it is now, but I do know that's one of the things my new camera automates even though digital seems more tolerant of over/under exposure than slide film. (It even lets me choose whether I want the order to be 0/+/- or -/0/+.) So I'm pretty sure the practice hasn't died out. I find it useful when I'm in a hurry -- when I want to concentrate more on composing quickly and tracking a moving subject than thinking about the exposure, and I know I'm in a fool-the-meter situation. (Another trick I use is a really lazy approach to 'zone' thinking: switch to spot-meter mode, pick different spots to meter on, use exposure-lock when I recompose, and pick the version I like best in editing later.)
And of course when shooting IR film, where the meter only gives a vague, unreliable idea of how much IR light there is in the scene, I bracket very widely. (I need to get a #89 or #87 filter and experiment with shooting IR in the DSLR. Instant feedback should mean not needing to bracket as much, because I should be able to get an idea how far to compensate from what the meter says that day.)
My only problem with auto-bracketing is when I forget to turn it off again after I'm done with it.