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Science Behind Overexposing Expired Film?


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So I heard the rule for shooting on expired film is to over expose by one stop for every decade past the expiration date.

 

My question is; does this mean it loses one stop in the shadows for every decade, or does the exposure shift downward overall?

 

Thanks to anyone who can help!

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The idea of overexposing expired film is to lift your picture information up the curve, so that it is above the base fog caused by aging and atmospheric radiation. Obviously, this means that the latitude of the film is reduced as you are pushing your highlights way up onto the shoulder of the curve.

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I think what happens is that the base fog level increases so you want to place more information above that and then print down to bury the fog. But there may also be a loss of sensitivity as well, which is another reason to rate the stock slower.

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Yeah I noticed my highlights were getting a bit blown out when I over exposed by 1.3 stops so the loss of latitude makes sense then. Perhaps I should just over expose by half a stop for 15 year old film?

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A lot of it depends on what you are photographing. If there are no dark areas or deep shadows, you may not need to over expose as much to stay out of the base fog. The amount of fog is going to depend on not just the age of the film, but how it has been stored. Fast film deteriorates quicker than slow film.

 

it's always going to be a crap shoot when using expired stock. Sometimes you get lucky, sometime you don't.

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What you don't want to do is take old film stock onto night shoots etc. Or even very contrasty exteriors. Overcast days in combination with slight overexposure is probably the way to get the best results from old stock.

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I've been shooting a lot of Kodak Portra from 2012 on Hasselblad recently and I rate the film at half box speed if I shoot in lower light and at box speed if in bright conditions.....

Probably no need. 2012 is yesterday unless it's been on a radiator. But Portra has plenty of latitude. I wouldn't do that for portraiture though. I used to use it by the carton.

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Probably no need. 2012 is yesterday unless it's been on a radiator. But Portra has plenty of latitude. I wouldn't do that for portraiture though. I used to use it by the carton.

 

 

Still use it all the time professionally......the 160 400 and 800...i told my clients i quit digital and they are liking it!

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I have 2x 400' recans of 5219, one marked 2009 and another one 2008. Based on this discussion I should rate them at 250, but what would it look like if I did shoot it at 500? Is it only going to be a lot more grainier with a little color shift? I know it's a gamble but for what I'll shoot it's ok to gamble.

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