RE: [APML] Expired films

[Philip Perkins <pgp@astrocruise.com>]

I agree with all the other comments that film can be good for a year or so 
past the expiration date provided that it is stored at low temperature in a 
fridge or freezer.  But there is a limit and degradation becomes gradually 
more apparent over time.  By the time a film is two years or more out date 
I think that degradation will be apparent in all cases.  The film will 
still record stars perfectly well, so the film may seem to be OK.  But 
stars are point sources of broadband light which will record on almost 
anything.  The real test is how the film records colours in extended 
objects such as Ha and OIII regions, especially faint regions.  Aging 
results in fogged emulsion.  Colours become less vibrant and colour shifts 
occur.  Ha regions will take on a dull muddy reddish-brown hue and faint 
detail will not be recorded.  But don't be misled by stars which will still 
record well - look at faint Ha regions to see if there is degradation or 
not, preferably comparing the result with a similar shot on fresh film.

--Philip

At 20:31 10/05/2004 -0700, you wrote:
>I've still got about 30-35 rolls of Supra 400 in the fridge. They start
>expiring next month I think. I'm going to try to use them up in the
>next year or so, but to this point I have noticed no degradation. Once
>they're gone, I don't know what I'll do. I have an idea I guess, the
>initials are: SXV-H9. Unless Kodak, Fuji, or someone else makes a
>mistake and accidentally makes another good color negative film, film
>will turn into a seldom used pastime for me. Maybe some pigyback stuff.
>Anyway, shoot away with no fear.
>
>Alan
>
> >   I have some Kodak Supra 400 rolls (the former emulsion) in the
> > fridge
> > which expired last month. Should I throw them away, or can I still
> > use
> > them with confidence? How accurate is the expiration date of a film?


Philip Perkins
<pgp@astrocruise.com>
Wiltshire UK & Luberon France
http://www.astrocruise.com

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