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Re: (meteorobs) Long Exposures/Reciprocity
In a message dated 97-04-16 13:03:46 EDT, you write:
<< HI George,
The film carries on where it left off.
I have never done really long exposures as I have found that you can
get the same results in 20 min.
>>
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So after a 40 minute exposure where an 800 ASA film dropped down to 15 ASA
equivalency, I can make a double exposure on the same frame during
daylight...if I considered it as having 15 ASA?
I can see how preflashing wouldn't change the ASA any based on what you
say..dot since the preflashing operation is only a fraction of a second...prior
to reciprocity failures occur. But I don't understand how the film would
recognize the difference between a short preflashing to the light it has
received from a dimly lit object during a 10 minute exposure?
George Zay