Re: Infrared sensitivity of Silicon PhotoDiodes

["Elton N. Kaufmann - Cycloid Fathom Group" <cycloid@xxxxxxxxxxxxxxxxxx>]

I too had toyed with the idea of an IR meter and became skeptical of the
market potential - even if the product was just a modification on an
existing meter (such as when Zone VI modified the Pentax spotmeter).  My
thought was to add a flip-in/flip-out filter so the ratio of IR intensities
(in the 700 to 900nm band)  in the scene to visible light could be
measured. Perhaps a different filter for the Konica folks could be used -
it gets cumbersome, but by noting the differences between the #87 and 87C
one gets an idea of how the light is distributed above 650nm.  Most of us
already have our rules of thumb about bright summer days versus winter
twilight scenes, but actually measuring the relative proportion of the IR
would add confidence for me (and would save quite a bit of bracketing and
therefore money I expect).
							EltonK


>Date: Wed, 7 Jan 1998 09:05:54 -0800
>From: Bill Agee <billagee@xxxxxxxxxxxxx>
>Subject: Re: Infrared sensitivity of Silicon PhotoDiodes
>
>>
>>This thread reminds me of a discussion I had some months ago about  the
>>possibility of manufacturing an IR exposure meter. I was talking to a
>>small electronics manufacturing concern that makes test equipment for
>>the photographic industry.  They indicated that it would be easy to do
>>but were not sure anyone would be interested.  Is anyone?  I have always
>>had pretty good luck metering (or guessing) IR exposure but it does seem
>>as though an IR meter would makes life easier. And exposure does seem to
>>be the most asked question from thosew just getting into IR work.  What
>>do you all think?
>>
>>Happy New Year!
>>
>>Howard Wells
>
>
>Maybe I am showing my ignorance, but I am not sure what value an IR meter
>would have. If it only measured IR light then what about the visible light
>that many of us that use ir film either unfiltered or with red #25 filters
>which do not cut off all the visible light.  It may be of some help to
>those who use the opaque filters that cut off all the light.
>
>The most valuable meter would be on that had a way to put the filter you
>prefer on the meter.  A meter that had diodes that replicated the spectural
>response of HIE exactly....then what about Konica...or Ilford?
>
>Bill Agee

Exhibiting fine-art and editorial photography
Cycloid Fathom Gallery
Elton N. Kaufmann, Chairman
P. O. Box 8129
Downers Grove, Illinois 60517-8129
USA
cycloid@xxxxxxxxxxxxxxxxxx
http://www.cycloid-fathom.com/gallery/
ftp.cycloid-fathom.com/group/uploads/

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