Re: Melles Griot filter info

[ADavidhazy <ANDPPH@xxxxxxxxxxxxxxxxxx>]

I decided to take another look at the spectral response of CdS cells and sure
enough, the average peak sensitivity is in the visible for both selenium and
CdS with CdS having somewhat better red and near IR sensitivity while silicon
cells seem to peak further out in the IR. So it seems that silicon cells would
benefit from some kind of limiting filter while CdS cells may have a relatively
low long IR wavelength sensitivity.                           

In any case, it is always prudent to take a look at the spectral response of
all the items that contribute to the making of a light or an IR exposure meter
or exposure "reading".

Going to lengths to make the meter spectral sensitivity match the film response
is the right thing to do. One may be able to get away with approximations and 
as long as one is aware of pitfalls associated with approximations and
improvisations then all is ok. But one can easily be misled by recommendations
made by inappropriately or incorrectly designed or used (!) equipment. 

g'day!

Andrew  o o  0 0 o . o  Davidhazy, Imaging and Photo Tech
         \/\/\/\/\/\/          http://www.rit.edu/~andpph
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