Is the question "Why did the OM-4 quench the shutter at 14S every time,
regardless of the amount of light?"
I validated Walt's figure, 1 sec. @ f/180 for sunlight exposure. The e-SIF
says the lower limit of Curt's 4ti is "approx. -5EV~19EV
at ISO/ASA 100, 50mm F1.4, normal temperature and humidity". I think John Lind
said that if the lower limit is -5EV at f/1.4, then
the linkages involved mean you "lose" one EV value for every smaller f-stop.
For example, if memory serves, at f/2.0, the lower
limit is -4. If you take it all the way out to f/180, like I did, you get the
lower limit is +9EV at f/180. After Walt (and
Shipman), sunlight is about EV15. So, going by the numbers, the 4Ti could
meter EV15, even at f/180 because, theoretically, the
lower limit would be 6 stops less light (+9 EV).
Practically speaking, the 4Ti wasn't designed for pinhole exposures, of course.
So, Curt, if you're pretty sure about that f/180
number, I'd try Walt's figure of 1 second, then try one with 1 stop more
exposure, using B and counting to
"two-one-hundred-thousand" out loud. You could bracket +2 stops by counting to
4 or course but I don't think reciprocity runs more
than 1 stop usually with an exposure on the order of one second.
Long story, short: 14S sounds like gross overexposure, assuming the pinhole is
close to the film plane. Gees, I guess a body cap
acts like about an inch of extension. Who wants to run with that calculation?
Interesting thread.
Lama
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