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Anonymous
>>82610 So do you not know what "notation" means? Here's a link for you: http://wordnet.princeton.edu/perl/webwn?s=notation
Anyway, the point I was making is that the *reason* we give aperture as "f/4" or "f/1.4" is that the amount of light that the lens lets in depends on both the focal length and the size of the aperture. So a 50mm f/1.0 has a 50mm-diameter aperture, but that would let in exactly as much light as a (monstrous) 200mm lens with a 200mm-diameter aperture, because they are both f/1.0. The f/whatever notation means that photographers don't have to do that math in their head for whatever lens they're using--50mm f/2.8 lets in the same amount of light as 100mm f/2.8 lets in the same amount of light as 135mm f/2.8 and so forth. Can you imagine how difficult it would be to manually figure out exposure with a zoom lens if exposure changed depending on the physical opening of the lens rather than the ratio of the aperture to the focal length? This is one of the fundamentals of photographic optics.
If you own more than one lens, or a zoom lens, you can easily test this yourself.
But you probably won't, because you probably already know this, because I'm probably just feeding a troll. And have made myself late for work in the process. Sigh.
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