Can extremely low temperatures cause speed loss?

laingsoft

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It's now coming around to the cold part of the year, and we're expecting temperatures around -30C to -40C. I'd like to shoot a bunch of rolls to see if I can capture some things like snow dogs or just some landscapes.

Should I overexpose by a stop or two? I know that ISO is determined at STP, and this is going to be substantially colder than stp, but how much does temperature influence exposure? I'm assuming that the pure photon to silver salt reaction likely won't change, but the dynamics of the speed increasing additives could change substantially, right?
 

mshchem

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Way back Kodak had some films that had a very slight change. I would be more worried about the camera and shutters etc.
 

BrianShaw

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... and worry about batteries, condensation, and static. Brittle film base too.
 

Vaughn

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I shot sheet film at -7C or so...while I did not notice loss of speed with the film, the operator had his issues.
 

wyofilm

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Very cold temperatures enhance film speed as I recall reading in Covington's astrophotography book. You might not be cold enough to experience it - as hard as that is to believe. My foggy memory tells -100C or so.
 

MattKing

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Old Gregg said:
And now I want to know which emulsions NASA used in those Hasselblads on the Moon!
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IIRC, Ron Mowrey (Photo Engineer) posted that they cross processed E4 transparency film.
 

wyofilm

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My foggy memory was faulty but on the right track. Cold cameras (dry ice temps < -175.8°C) were used to eliminate reciprocity failure. Covington doesn't appear to mention anything about film speed.

It would be interesting to know if reciprocity failure is reduced or eliminated at -30°C or so. As MSCHEM mentioned I would be worried about shutters. It might be worth trying some long exposure when our mercury drops this winter, but without stressing camera hardware. Uncovering a shutterless lens? Or try using a lesser backup camera.
 

MattKing

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wyofilm said:
My foggy memory was faulty but on the right track. Cold cameras (dry ice temps < -175.8°C) were used to eliminate reciprocity failure.
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Which is another way of saying that low temperatures enhance the film's sensitivity to very, very low levels of light.
 
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laingsoft

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For what it's worth, I've shot a fair amount In the -10ish range before, and you do start to get issues with focal plane shutters, at least on the cameras that I have. My TLR's don't seem to have the issues though, so that's probably what I'm going to end up using.

Reducing reciprocity failure is interesting though, I'm guessing that as temperature gets lower, the curve is going to shift from a logarithmic curve to a linear one, right?
 

wyofilm

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laingsoft said:
I'm guessing that as temperature gets lower, the curve is going to shift from a logarithmic curve to a linear one, right?
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It would be great to know. I don't!
I don't think that -178°C is magical regarding RF - it is just that the dry ice is convenient to work with. What was interesting when I went back to Covington's book is that he used the word 'eliminate' regarding reciprocity failure. As someone who has winters akin to yours, I'm looking for any benefit to the cold! Maybe when we hit -30°C reciprocity failure goes away or is at least reduced.
 

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I've shot Tmax 100 and HP5+ in -25 C with no noticeable difference in either direction. It was also in Pentax 645 with no issues with camera either, shutter or otherwise. I only recall my fingers not liking it for extended periods.
 

Jojje

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Shutters operate sluggishly below -20C. Best to avoid very short times where the error is greatest. One can, of course, "underexpose" on purpose.
 

Vaughn

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MattKing said:
Which is another way of saying that low temperatures enhance the film's sensitivity to very, very low levels of light.
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Interesting way to put it. Maintaining normalacy as an enhancement. Certainly an expression of our times!
 

Sirius Glass

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Cold enhances reciprocity, but advance film slowly because static electrical discharge can mess up the negative.
 

MattKing

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MattKing said:
Which is another way of saying that low temperatures enhance the film's sensitivity to very, very low levels of light.
Click to expand...
Vaughn said:
Interesting way to put it. Maintaining normalacy as an enhancement. Certainly an expression of our times!
Click to expand...
To my mind, it makes reciprocity failure much easier to understand.
In truth, this type of reciprocity failure has nothing to do with the long exposure times people associate with it.
It has everything to do with the really low light intensity that makes those times necessary - the film doesn't respond the same way to light that dim.
Films with excellent low level reciprocity behavior are responsive to those very low levels of light intensity. Other films are not so responsive.
 

Vaughn

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Then no matter how we wish to describe it, basically in the sub-zero C temperatures that we might be crazy enough to work in, the basic film response to light will remain the same, except if for some reason we want to stay out in the cold even longer and make long exposures...our exposures won't have to be extended as much as usual since the RF is less in the cold.
 
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