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[OM] Re: [OT] Expired Reala

Subject: [OM] Re: [OT] Expired Reala
From: Moose <olymoose@xxxxxxxxxxxx>
Date: Tue, 13 Jan 2004 17:57:15 -0800
I see lots of replies, cute and otherwise, but none particularly responsive.

The light sensitive emulsion on film is a dryish chemical soup and the 
chemicals aren't all that stable over time, particularly at elevated 
temperatures. So the makers mark the film with an expiration date that 
is about where one can expect changes from target performance that start 
to be noticeable under some guesstimate of consumer storage conditions. 
Color balance will generaly be first to be noticeable. The thing is, the 
change is gradual and continuous, not sudden, under reasonable storage 
conditions. Put the film on the back shelf uf a car in the sun for a few 
hours and it can go psychedelic way before the marked date. For slide 
film, you really have to watch it. For negative film that will be 
auto-printed, any modest color shift will be lost in the auto color 
balance settings of the printer and using film several months out of 
date that has been stored at modest temps tends to be unnoticeable.

Some 'pro' films are actually the same emulsion as a consumer film. The 
difference is that the film is aged until it reaches its target 
performance, then kept refrigerated when warehoused, transported and 
stored at the retailer, so it will age as little as possible before 
being exposed and processed. So most of the reason it costs more is more 
expensive storage and handling and lower volume. Of more importance to 
many pros than some absolute in color accuracy is great consistency from 
roll to roll and batch to batch. The consumer version is sent off as 
soon as it is made, ages from less than ideal in one direction through 
its best and off beyond it during its shelf life.

Moose

Jim.Timpe@xxxxxxxxx wrote:

>>-----Original Message-----
>>From: olympus-owner@xxxxxxxxxx 
>>
>>What happens to Reala when it expires?
>>    
>>




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