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balance settings of the printer and using film several months out of
date that has been stored at modest temps tends to be unnoticeable.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?
>>
>>
The olympus mailinglist olympus@xxxxxxxxxx
To unsubscribe: mailto:olympus-request@xxxxxxxxxx?subject=unsubscribe
To contact the list admins: mailto:olympusadmins@xxxxxxxxxx?subject="Olympus
List Problem"
|