Is there an effect of temperature on film exposure?

Question

It is obvious that temperature plays a most critical role in developing films. It is not clear to me, though, what effects temperature might cause at the time of exposure.

I didn't stumble upon any reference to exposure temperature in datasheets of films I personally use. This suggests that there's nothing relevant for the photographer going on. On the other hand, as this is a chemical reaction there should probably be some effect.

I found some suggestions that there might be an effect on the reciprocity error. Are there some reliable sources with data that could prove it?

Is there any effect of high/low temperature on film exposure in negative/positive bw/color film? And if yes, how do you account for these effects? Should I spent a thought on this when going to take photos on film in extremely cold or hot environments?

Answer 1

Cold reduces reciprocity failure, and is used particularly for astrophotography. See http://en.wikipedia.org/wiki/Photographic_hypersensitization#cite_note-15.

My own experience with Kodachrome (RIP) was that very cold weather reduced the blue-green cast of nighttime skies and cityscapes. Note that this could lead to frostbite, by the time the camera is cold enough to matter, and the camera should not be allowed to warm up where humidity can condense on or in it. See the following, from the above URL:

Webb, J. H. (1935). "The Effect of Temperature upon Reciprocity Law Failure in Photographic Exposure". Opt. Soc. Am. 25: 4.

Hoag, A. A. (1961). "Cooled Emulsion experiments". Publications of the Astronomical Society of the Pacific 73: 301.

BTW, a few posts here seem unfamiliar with reciprocity failure: for long exposures, e.g. a minute or longer, the film behaves as if it were less sensitive and therefore requires a longer-yet exposure. For color film, this is not uniform for each layer, and produces a noticeable color shift (e.g. sickly green for Ektachrome). Cold reduces this. What might be happening on a quantum level is that at higher temperatures, the excitation of the silver halide/sensitizer complex is lost before a reaction occurs.

Answer 2

What I know is the following (own experience + a few forums read here and there, often on flickr) :

• film may react to strong temperature gradients - I am not talking about the emulsion, rather mentioning the film itself : its curvature may change ;
• in especially cold nights, I've often read that people (astro-photographers, especially those shooting medium or large format film, due to the surface exposed) might have trouble ensuring film's planeity over long periods of time (so they end up tweaking their film backs for improved mechanics) ;
• in hot climates, film expires more quickly, so it's better to think about it before leaving one's camera in the car in the middle of the desert ;
• reciprocity failure : I haven't researched this issue in relation to the environmental temperature.

Answer 3

As you deduced from your examination of data sheets, the effect of temperature on film sensitivity is very slight, certainly less than half a stop within the normal weather range of 0°F to 100°F / -18°C to 38°C, so long as we are talking about brief exposures (not time exposures). You may want to check with Kodak for details. With extremely long exposures there may be a slighly greater effect. This site discusses related issues:

storage and handling of mp film

Since light is pure energy, it does not get cold. The reaction of silver halides to light is not a purely chemical one; it is a photo-chemical one, and hardly affected by temperature variations within the range that is safe for humans.