Have you tried readings in normal light at 800 & 400?
Tom
On Saturday, December 08, 2001 at 7:23, Curtis P. Hedman
<olympus@xxxxxxxxxxxxxxx>
wrote re "[OM] Help! OM-4T Film Speed problem" saying:
> I recently tried taking some Christmas lights photos with my 4T, using ASA
> 800 film. While taking the shots (in AUTO mode), it seemed like the
> exposures were too short, and when the film came back, most of the frames
> were severely underexposed - except for a few which I shot using the "B"
> setting and timed myself external to the camera. I then started fiddling
> with the camera, firing off some shots with lens cap in place (film loaded,
> of course). I found that, at the ASA800 setting, the exposures were running
> 8-10 seconds at f/2.... shifting to ASA400 resulted in 3 minute exposures!
> Thinking the contacts might be dirty I ran the selector back and forth a few
> time, and then seemed to get the long exposures at a number of ASA settings.
> When I repeated the experiment a day or so later, it was back to short
> exposures at ASA800, long at ASA400. Seems that the camera doesn't like the
> 800 setting! Anything below 400 seems to work OK. Anyone have any
> suggestions? Could there be a bad spot on the encoder or whatever, or
> persistent dirty contacts? Are there any other experiments I can try to
> narrow things done a bit? I did do a 'dark current' check - at ASA 3200 and
> f/2 (but lens capped), the meter read 1/4 second, which the list archives
> suggests is about right. I did find that even at ASAS25, the longest
> exposure the camera will deliver is 3 minutes, not the 4 minutes everyone
> seems to claim. Do I need to worry about light entering through the eyepiece
> during auto exposure, or does the mirror completely block off any stray
> light during exposure?
> Lots of questions! Hope someone has some suggestions..... Thanx in
> advance.
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