Heads up about that expired film you're hoarding

I just read a study from the Rochester Institute of Technology that showed color film loses about 20% of its speed per decade, even frozen. I found a roll of Portra 400 from 2010 in my freezer and the shots came out two stops underexposed. Anyone else have a good rule for shooting old stock?

2 comments

2 Comments

valallen6d agoTop Commenter

That Rochester study is spot on. I had the same thing happen with some frozen Ektar 100 from around 2012. My rule now is to add a stop per decade for anything stored cold, and two stops if it was just in a closet. It's not a perfect science but it saves a lot of wasted shots.

the_mila6d ago

That per-decade rule from @valallen is smart for saving shots. Makes me wonder about the film's original age though. Like, was that 2012 Ektar fresh when frozen, or already sitting on a store shelf for two years? The clock starts at manufacture, not when you buy it. A roll from a cold-stored brick shot in 2015 might act totally different than one from the same brick shot now. The batch history gets lost.