Archived posting to the Leica Users Group, 1997/09/24

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Subject: Re: 90/2.8--internal reflections
From: "Jacques Bilinski" <jbilin@axionet.com>
Date: Wed, 24 Sep 1997 21:53:32 -0700

> 
> The inverse square law doesn't apply to reflected from the subject you
are
> photographing. You'd think it would, but it doesn't. It only applies to
> light from the light source to the subject. 
> 
The reason it doesn't apply is that as you move twice as far away from a
subject you will only get one quarter of the light from each square
centimeter on the subject, but you will also cover 4 times as many square
centimeters, so the result is that the exposure doesn't change.