In a message dated 11/10/04 9:30:24 AM, s-walters@comcast.net writes:
A vacuum back will not stop film creep. The vacuum will keep the film flat
but cannot possibly constrain lateral changes in the film's dimensions.
Film creep is caused by both humidity and temperature changes. Increasing
humidity causes the film to expand and decreasing temperature causes it to
shrink. Humidity is the more common problem. You can either "acclimate" the
film in advance of shooting (Kodak told me this was the best approach, allow
about 30 minutes for the film to stabilize in its environment) or try to
keep it dry all the time by purging. I tried the both nitrogen purges and
temperature control on 6x9 cm film but was never able to stop it completely.
I corresponded with Kodak on this and they gave me the coefficients of
expansion for both humidity and temperature for E200 and TP. I can dig them
up if you want.
Steve...
www.StarryNights.us
Interesting information.
I agree with the temperature acclimatization viewpoint.
However, I've found that using a vacuum back and dry N2 does 'tame the beast'.
The only other alternative would be to use a rigid receptor and that would mean crossing to the dark side.
Kent Kirkley
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