T3D Re: Exposure at bbellows extension! (TECH-3D digest

["William J. Carter, Ph.D." <wc@xxxxxxxxxxxx>]

At 06:13 PM 9/21/98 -0600, Harry Richards wrote:

>  I would think that magnification would be more important than focal
>length.

When taking close-ups, where the lens is extended to any appreciable degree,
one must apply a "bellows factor" to avoid under exposer. What that does is
compensate for the fact that light falls off at the square of the distance.
As I recall, a 1:1 enlargement requires a 4:1 extension?


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End of TECH-3D Digest 362
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