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gmfotografie
7-Jun-2014, 06:24
hi guys, can you help me with long exposure times for kodak portra 160?

noah a from the forum tells us:

Up to 1 sec (metered) I shoot as metered.
5 sec (metered)=10-20 sec
10 sec (metered)=30 sec-1 minute

does this work for you?

i use often the reciprocity app but i cannot find portra 160
only the 100/400 portra ... ?! is it the same?

how is your experience with this film and how calculate the exposure?

best micharl

Bruno Gil
7-Jun-2014, 08:30
Doesnt the reciprocity rule applies to film instead of ASA? Im newbie to LF, but i shoot MF film
Cheers

Daniel Stone
7-Jun-2014, 11:15
nothing beats testing for your own workflow(and if you use a lab, their accuracy of "normal" processing). Not to mention your metering technique(and meter's actual accuracy)

Portra films are able to handle a good deal of over-exposure, and to a small degree, some under-exposure(to achieve "ideal" results). I've shot Portra 400 @ ASA 25 before(so a 4 stop overexposure from box speed), and while things were VERY washed out, there was still a recorded image there, albeit extremely low contrast and color fidelity was shot to sh**. Some might like this look however, and a good deal of the wedding people toting Contax 645's around now like this washed-out look that's somehow become somewhat synonymous with "shooting film".

I can only suggest that you shoot a few test sheets at varying exposure times(even during the day, just stop WAAAAAY down), and get them processed normally. Then you can find out your own data, and observe how the film reacts according to your testing procedures. You might also want to see if Kodak has published data for Portra 160, I know that for many professional films in the past, they've posted "recommended"(again, it's best to have your own data to back theirs up, since you're the photographer and might have differing standards to theirs, as the manufacturer) times for reciprocity adjustment.

I've usually erred in the +1-1.5x stops/metered exposure on color negative film exposures in the 1-2s+ range. I've never done much scientific testing myself, simply because the majority of my shooting isn't in that time slot. And the films I do use for said photographs(usually Provia for color these days) have posted data that shows almost no reciprocity failure in the multiple minute category. Which is more than enough for me and my shooting.

Test, test and test. It's cheaper to shoot 4-5 sheets doing your own testing than waste time, energy and more money on burnt shots and experiences when you could do things right because you are prepared, when you have a photograph to make.

just my 2

-Dan

gmfotografie
8-Jun-2014, 00:59
Test, test and test. It's cheaper to shoot 4-5 sheets doing your own testing than waste time, energy and more money on burnt shots and experiences when you could do things right because you are prepared, when you have a photograph to make.

i will do it, thanks

RHITMrB
8-Jun-2014, 23:45
Empirically proven data I posted a while back: http://www.largeformatphotography.info/forum/showthread.php?106441-Portra-160-and-400-Reciprocity-Failure