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Waynemel
Tinkerer
Username: Waynemel
Post Number: 52
Registered: 08-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 02, 2010 - 03:53 pm: | 
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As I looked outside today and it was -20C, I wondered if the cold temperatures affect the meter readings in cameras with selenium cells (or any other type for that matter). I would suspect the cold may have an effect, since the basic process is chemical and cold generally slows down chemical reactions.
Does anyone know? |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1031
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 02, 2010 - 08:04 pm: |
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I'm not aware of any such effect in light meters. |
Karl
Tinkerer
Username: Karl
Post Number: 42
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 02, 2010 - 08:42 pm: |
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If you mean do light meters work as well at -20C or +20C I think it depends if the meter is battery powered or not.Batteries work less well at low temperatures so this may effect the meter,but if you use a selenium meter it should not be effected, as light makes the cell work.The more light,more current less resistance.No batteries required.I think the film in an unprotected camera may be more at risk at very low temperatures for long periods.I have heard of film breaking if put under stress,such as rewinding.Keep the camera under your jacket is the answer I think. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 38
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 02, 2010 - 09:07 pm: |
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I was going to say that I've never heard of this effect with selenium-cell meters; batteries could indeed be affected adversely by cold, as explained above. Keep in mind that there's no chemical reaction occurring; it's a, um, photo-something kind of reaction (electrons getting knocked off by photons, dontcha know), so the usual business of the reaction being slowed by low temperature doesn't apply here.
I thought of doing a test by putting one of my selenium meters in the freezer and trying it cold, but thought better of it, as that might be a destructive test. Selenium cells aren't damaged by exposure to light, as some suppose, but by moisture, which could well condense on them if frozen and then put into a warm room. In the absence of moisture, they seem to last, well, forever. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 183
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 05, 2010 - 07:42 am: |
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Temperature effects meters. Keep it in your pocket till you need it.
Zinc air batteries will stop working at cold temps. Any other battery will be at reduced voltage or completely depleated if weak. |
David_nebenzahl
Tinkerer
Username: David_nebenzahl
Post Number: 39
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 05, 2010 - 11:35 am: |
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Yes, it affects meters that use batteries. Not so much selenium meters that don't use batteries. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 1035
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 05, 2010 - 08:55 pm: |
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I agree, perhaps my answer was oversimplified: Cold does affect batteries. It is the meter cells themselves that I was referring to above. |
