06 August 2008


Camera Works: an aperture and f-stop teaser

Here's a teaser for tomorrow's installment of Camera Works. In the two photos below we're looking (once again) at my main Nikon lens, front and back. It has a focal length of 50 mm, so it's a "normal" lens.

I know, without measuring it, that the open aperture you see letting light through the middle of the lens is 61/4 mm across at this setting, which is f/8 on the lens's aperture dial:

50mm f/8 lens front 50mm f/8 lens rear

Tomorrow I'll talk about how I know, why it has that diameter in the first place, and why, for lenses, 22 is smaller than 4.

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It's "normal" for 35mm film (and 35mm CCD).


Oh yeah, that topic is going to be a whole article in itself, probably next week.