Walt Wayman wrote:
>"The lens aperture is simply the diameter of the lens opening, expressed as a
>fraction of its focal length. Thus, a lens of 4-inch focal length with a
>diameter of one inch has a relative aperture of 4/1, or 4. the aperture
>designation is expressed as f/4, indicating that the aperture is the focal
>length/4. Another 4-inch lens that has a diameter of 1/2 inch would be an f/8
>lens.
>
He also wrote earlier:
Moose,
I've never heard an f-stop defined by its relation to the front element.
Well, now you not only have heard of it, but are quoting it. :-)
Moose
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