Re: [APML] Speeding up film with cold weather

[Mark Bohrer <lurchl@ix.netcom.com>]

I should probably have qualified my response to state it applied to 
exposure times 30 seconds or less. For hour-long exposures and any film's 
possible reciprocity range, all bets are off.

The thirty-second limit is approximate; I've gotten good results rating 
E100S at ISO100 on late December nights over Aspen, CO with 30 sec and 
F2.8. Similar exposures (and some shorter) also worked at Mesa Verde in 
winter. Truly, if winter sports shooters for ESPN had to worry about film 
speeds or digicam sensitivities increasing in cold temps, they'd lose their 
minds and start carrying thermometers...


>--- Mark Bohrer <lurchl@ix.netcom.com> wrote:
> > Cold temps may buy you less dark noise with
> > CCD-based cameras, but that's it.
>
>Hi Mark,
>
>I'll quote from the book by Jack Newton and Terance
>Dickinson, page 108.
>
>"For every drop of 20 Celsius degrees (35 Fahrenheit
>degrees) most films gain about one f-stop; that is, a
>400 speed film acts like 800 speed film around 0
>degrees C (32 degrees F) and like 1600 speed film at
>minus 20 degrees (-4F), and the process keeps going.
>At minus 40 degrees (-40F), a 400 speed film is
>running at about 3200 speed. Once again, these are
>rough guidelines, and they vary from one film to
>another, but when the temperature gets close to
>freezing or below, all films show this increase in
>speed to some degree."
>
>For whatever reason, they seem to feel that this is a
>real effect. All I know is that if I can get in a
>couple of hours what has been taking me 4-5 hours to
>get, I think I'm going to look into it.
>
>Alan
>
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Mark Bohrer
www.kokophoto.com
Pro mountain bike racing on the web


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