Re:cds cells and such

[P3D romney <romney@xxxxxxxxxxxxxxx>]

Correction...I guess, as I said,  I really am not a  solid state expert,
or I am suffering memory loss.  Sorry. I checked tonight and the Albrecht
digital shutter tester uses an IR  photo diode or a photo transistor, not a
cds cell. . You can get them at Radio Shack. As per accuracy of readout
with a 10khz clock at 1/1000 sec. , it can be no greater than 10% since the
digital display can only read 9.9ms, 10.0 ms 10.1 ms...etc..Nothing in
between. See? The real trouble with shutter speed measurement is the
brighter the light you use... the slower the shutter appears to be. This is
on leaf shutters. This is because with bright light the digital timer
begins to count when the blades are barely open and only stops when they
are nearly closed. In dimmer light it might not gate until the blades were
nearly open...Long ago they let shutters be 1/3 slow and still pass
standards. Most 1/1000 second cameras were really about 1/700 sec. then. A
1/500 sec Compur Rapid is really 1/400 sec, and the 1/150 sec Realist
shutter would have been called !/200 sec. if sold  by a less reputable
manufacturer than David White. Hope that helps...ED.



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