I always understood the f number to refer to the ratio of the actual
scenery light intensity appearing inside a lens. Ex: f2 would let in
1/2 the light intensity. Ergo, wouldn't f < 1 imply that light
amplification was taking place.
Not quite. "f" is the ratio of focal width to focal length, and
depending on the lens, may have little to do with the actual light
coming through.
When you adjust the diaphragm, for example, you are changing the
focal width, and thus the ratio.
So a 50mm f0.5 lens, for example, would have a 100mm focal width.
: Jan Steinman <mailto:Jan@xxxxxxxxxxxxxx>
: Bytesmiths <http://www.bytesmiths.com>
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