At 01:59 AM 6/27/99 -0700, you wrote:
>Light value is proportional to the square of diameter of the light source.
>The half moon is half a circle with the same diameter as a full moon, thus
>half the light. If a half moon was a circle one-half the diameter of the
>full moon, then it would yield 1/4 the light.
>
>Like other electromagnetic radiation, light obeys the "square law," as it
>falls off with the square of distance, which might be what you're thinking
>of. But the half moon is still about the same distance from us as the full
>moon... :-)
>
>: Jan Steinman
If I shoot a side-lit flower against a dark background, exposing for the
proper values of the flower itself, and not an average of the whole scene,
I should get a properly exposed photo of a flower against a dark
background. If I have two flowers of the same value in the scene, my
exposure doesn't change.
Why is it different with the moon? The moon is not a light source per se,
but reflected light, just like the flowers.
Joel Wilcox
Iowa City, Iowa USA
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