T3D Re: (Illuminnation of optics to film) TECH-3D digest 480

["bobh" <bobh@xxxxxxxxxxxxxxxxxx>]

RE: Boris has cleverly noticed that light from lens to center has a 
shorted distance to travel that from lens to corner. This is a long 
standing fact known as Cos$ law..on very wide angles (like the 15mm 
Zeiss f/8 for 35mm frame) a graduated filter was supplied to 
compensate. On near normal lenses there is some compenstation in 
projection or enlarging in that the same effect happens going the 
other way...so negative thinner in corners prints hotter in print.
Some new asphereic lenses like the Sigma 14mm linear AF seem to be 
remarkable compared to the older Zeiss lens of 20 years ago.  BobH


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