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wildbillbugman
07-05-2009, 02:38 PM
PE,
This just poped into my mind this AM: Do you know of any studies of B&W film which adress the effecy of temperature of the film at the time of exposure. Something tells me that Kodak might have done lots of this. I am wondering how elevated temperatures might affect the speed,contrast,deffinition and accutance of film.
Thanks,
Bill

Photo Engineer
07-05-2009, 02:56 PM
Bill;

I know of studies, but offhand I don't know the results. I never paid much attention to them. Many were conducted for NASA for the space program.

PE

wildbillbugman
07-05-2009, 03:16 PM
PE,
To your knowledge, has there ever been a camera with a heated,or cooled, plate behinde the film?
Thanks,
Bill

keithwms
07-05-2009, 03:52 PM
Seems to me that heating would only increase fog.

Cooling might reduce it if the whole canister is atmospherically sealed (otherwise condensation would be a killer).

I am guessing that hypered film will retain its faster speed somewhat longer if cooled.

Photo Engineer
07-05-2009, 05:33 PM
Bill;

We had a heating element designed for just that purpose, but AFAIK, no tests were run. We were working towards heat processed films.

Keith;

AFAIK, heating to 200 C or thereabouts has no effect on fog. I never went higher, but that is one test I did run. Also Kodak ran tests for the astronaut films that encompassed very high and very low temperatures and transitions between vacuum and air. The air had high and low pressure and high and low oxygen. The only thing I remember is that vacuum had no effect whatsoever, at least in the times that were tested.

PE

wildbillbugman
07-05-2009, 06:49 PM
Heck,
Now I have ro reinvent NASA! Something tells me that,if the USA ever revisits the Moon, film will not be in the Astronauts backpacks. They will use that digital Hassi,and loose 20% of what they actualy see.
BTW,I am kidding about reiventing NASA. I will do nothing along the lines of temperature and film. It was just a matter of curiosity.
Bill

keithwms
07-05-2009, 08:29 PM
Ron, 200C??! What film was that? I'd guess that the base itself would be unstable at that temp. Was it under vacuum or inert gas or something?!

Ray Rogers
07-05-2009, 09:37 PM
Ron, 200C??! What film was that? I'd guess that the base itself would be unstable at that temp. Was it under vacuum or inert gas or something?!

I had the same reaction.
I imagine they used glass, but note that even gelatin will begin to burn or char if the temp gets much higher....

Photo Engineer
07-05-2009, 09:47 PM
That was one of Grant Haist's thermally processed materials. It was mentioned in another thread here today.

I have gone hotter than that, but 200 C is just fine for me and the film was Estar.

PE

Larry.Manuel
07-05-2009, 10:57 PM
For astronomy, there used to be cold cameras, which [I suppose] reduced reciprocity failure. Typically dry ice was used to cool the film and phenomenal results were common. A major problem was to keep frost from forming on the film, and I think some cold cameras had an optical "plug" of glass in contact with the film, or else an optical window between camera and telescope, with the camera cavity purged slowly with dry nitrogen. Pros worked this stuff out very well, and amateurs built their own and some amateur cold cameras were produced commercially. I recall dry ice is -77C approx.

I recall a friend of mine, who lived in Bath, Ontario, on Lake Ontario. He dragged his telescope way out on the frozen lake one winter night for astrophotography [back in early 1980s]. It was about 40 below, and he reported better film sensitivity. This might be an anecdotal tall tale, but it fits well with our Canadian psyche. "Ten months of winter and two months of bad sledding".

Ray Rogers
07-06-2009, 11:47 AM
a)
Ron, so the no fog increase with heat up to 200 deg. C. you mention in post #5
was not with a traditional emulsion?

b)
These two statements in posts 5 & 9 seem a bit inconruent:

#5
AFAIK, heating to 200 C or thereabouts has no effect on fog.
I never went higher, but that is one test I did run.
#9
"I have gone hotter than that, but 200 C is just fine for me and the film was Estar."

Did you mean to put a knot in #9?
---
c)
At what temperature does Estar melt?

Photo Engineer
07-06-2009, 02:01 PM
a) it was a traditional Br/I emulsion.

b) Not so. I used 200 C for processing and had no fog, but I did heat samples of support higher, I just did not make an image on the samples AFAIK. I have forgotten the details of peripheral tests. Sorry.

c) Over 250 deg C. It does deform at the edges at 200 C IIRC.

PE

Ray Rogers
07-06-2009, 05:11 PM
I used 200 C for processing and had no fog, but I did heat samples of support higher, I just did not make an image on the samples AFAIK. I have forgotten the details of peripheral tests.
---
Over 250 deg C. It does deform at the edges at 200 C IIRC.

PE

Ok. Thanks for the clarification.