Is hot film faster?

I've heard that temperature doesnt change the sensitivity of film but I may be wrong. I know cold film is the same speed (not slower).
 
I think I recall that the incoming light does not cause a chemical reaction. It just affects the silver-halide crystal so enabling, later on, the developer-agent to "grow" the affected speck on the halide crystal into silver. That has something to do with donating electrons and breaking down the molecules in the crystals - it is a straightforward reaction and easy to understand, except I can't remember what exactly.

As my chemistry was done more than 24 years ago, I am a bit hazy on the details. Perhaps someone else can provide a good "what really happens" link ?

Whether extreme heat is going to negatively (pun intended) affect the silver halide crystal structure is another question of course, not to mention the film-base or camera !
 
No, hot film is not faster. However, you can use gases such at nitrogen to increase film speed - called hypering.
 
It must be me then, in the negatives from holiday this year I’m seeing a lot of variation in density roll to roll, more than my normal haphazard methods produce. We had very hot conditions this year, 50° in the town centre one day, and I seem to have switched from tending to under-expose to tending to over
 
Sparrow said:
It must be me then, in the negatives from holiday this year I’m seeing a lot of variation in density roll to roll, more than my normal haphazard methods produce. We had very hot conditions this year, 50° in the town centre one day, and I seem to have switched from tending to under-expose to tending to over
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Are you sure the temperature was not affecting the shutter? Or if it had an automatic diaphram, the aperture?
 
Finder said:
Are you sure the temperature was not affecting the shutter? Or if it had an automatic diaphram, the aperture?
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No not sure of anything, just a tendency to be a bit over-exposed, a stop or two in the daytime mainly, across 18-20 rolls from three bodies, one mechanical and two electronic, r2a and r3a and an L
I think almost everything will print OK so it’s not a big problem, just unsure what I did differently
 
Sparrow said:
No not sure of anything, just a tendency to be a bit over-exposed, a stop or two in the daytime mainly, across 18-20 rolls from three bodies, one mechanical and two electronic, r2a and r3a and an L
I think almost everything will print OK so it’s not a big problem, just unsure what I did differently
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If the area was very different than from what you are used to shooting, sometimes that can cause exposure problems. I had a difficult time figuring out the light in Tibet when I went.
 
We go to the same place each summer so I know the light, Fuji 400 as usual, same lab I normally use back here in the UK. If anything it wasn’t as bright as normal, quite hazy at times, but it was extraordinarily hot
 
I would expect the speed of nonchromogenic b&w film to be rather weakly dependent on temperature, because the photochemical reaction is on a rather different energy scale than the small variations in ambient temperature. if there were any variation at all I would expect the film to be very slightly faster at higher temps.

On the other hand, with colour neg film or slide, I would expect a somewhat stronger temperature dependence, simply because in those cases multilayers and couplers are involved. I don't know if higher temps would make the film faster or slower; there's no reason I can think of to expect a simple behavior- it might even be faster in one layer and slower in another, I wouldn't know how to think about that offhand. I would guess (guess) that the couplers become less efficient for temperatures outside the ~22-27C optimal range and then one would foremost see reduced saturation, and perhaps a change in dependence on colour temperature. Some couplers may have different temp dependence than others, and then you'd get colour shifts. With chromogenics that may be a bigger issue as well.

Of course, the temperature dependence during processing is quite extreme for all films.
 
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keithwms said:
I would expect the speed of nonchromogenic b&w film to be rather weakly dependent on temperature, because the photochemical reaction is on a rather different energy scale than the small variations in ambient temperature. if there were any variation at all I would expect the film to be very slightly faster at higher temps.

On the other hand, with colour neg film or slide, I would expect a somewhat stronger temperature dependence, simply because in those cases multilayers and couplers are involved. I don't know if higher temps would make the film faster or slower; there's no reason I can think of to expect a simple behavior- it might even be faster in one layer and slower in another, I wouldn't know how to think about that offhand. I would guess (guess) that the couplers become less efficient for temperatures outside the ~22-27C optimal range and then one would foremost see reduced saturation, and perhaps a change in dependence on colour temperature. Some couplers may have different temp dependence than others, and then you'd get colour shifts. With chromogenics that may be a bigger issue as well.

Of course, the temperature dependence during processing is quite extreme for all films.
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One thing I did notice on my “draft” scans was some muddy looking blues, which again is unusual it that light

I’ll run off the part rolls that are still in the bodies on the next sunny day and see what happens
 
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High temperatures can damage the latent image. In the early 1960s, I was taught to process exposed film as soon as possible. In an earlier age, itinerant photographers would travel with chemicals and tents for immediate processing. Until the 1980s at least, unexposed film would not keep for very long. Emulsions have become much more stable now.
 
I still process as quickly as I can, a discipline learned in the 70s and 80s, I remember Ektachrome going green after a few months delay
 
Ah yes, it's definitely a good idea to process ASAP. Indeed that is probably a larger effect than the actual temp at capture time.
 
Was the UV higher than normal in the area? If the film you used was sensitive in the UV range that could result in a fogging effect.
 
I doubt that extreme temperatures would "speed' up the film. The effect would most likely be increased base fog on bl/w an or severe color shift on slides. Extreme cold will slow down emulsion speed though as well as introduce the chance of cracking emulsion and/or static "flashes".
The biggest problem with color stock in extreme heat is that emulsion and backing might separate or start disintegrating. I have done some shooting in temperatures above 50+C and the older Ektachrome was definitely affected, including "melting" marks on some frames. The most stable film for color in those temperatures was kodachrome as it is inherently a multi layer black/white film (the color is added in the processing). If you combine shooting in high temperatures and high humidity - watch out! I have had the emulsion stick together and destroyed the rolls!
Black cameras can also become very hot in direct sunlight! Modern electronics is surprisingly tolerant of heat, but if the camera is exposed to direct sunlight for a long time, the electronics might show some strange behaviour. The good thing is that they usually go back to normal behaviour when cooled down. Depending on the tolerances in the camera, heat expanded shafts or shutters can start jamming or slowing down too.
 
The film was Fuji superia 400, I’ve used it in the same location for many years, I expect a tendency to go blue-violet in the middle of the day, the family holiday so I have to be able to provide colour prints for them, and I then de-saturate it for my own stuff.
It could have been the cameras I suppose certainly one day one was too hot to hold after being in the car boot/trunk for some time, the covering is marked where I picked it up as if the glue had softened
 
If my Alzheimer does not betray me it was exactly yhe opposite
Astrophotographers used to supercool the film with liquid N2 for long exposures to hypersensitize and keep the background fog in check
don't know the chemicla basis but I guess that within -10 to 40 C there will be not a noticeable difference
 
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