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11-06-2018, 02:13 PM   #1
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Push Portra 400 or Not?

Hello,

I am experimenting with Portra 400, the goal is to shoot this film at EI 500-640 to give some extra speed, and would eventually consider using it up to EI 800-100 range. I would like some suggestions on how to develop the film under these two conditions. I am more interested in the EI 500-640 range as this allows me to no longer stock Portra 800 and Lomography 800. I've heard that for 800, Portra 400 does well with no push, and for 1600, push 1 stop would enough. I am especially interested in that, since pushing film in my preferred lab here in the US adds a surcharge, and pushing C-41 film is not available from my preferred lab in China.

Sincerely

11-06-2018, 02:20 PM   #2
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There's some tidbits of information about pushing C-41 via stand development. I don't dev C-41 myself yet but have considered starting and would love to explore that method.

Not sure how useful this reply is. Hope you can figure something out.
11-06-2018, 06:26 PM   #3
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I haven’t pushed Portra 400, but with Ektar 100, I’ve been able to push it to 200 with standard development and not see a difference.

Note: I am developing at home and my chemicals were mixed that day.
11-06-2018, 08:44 PM   #4
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Negative films are pretty forgiving - you can pull them several stops without issue, pushing film involves more compromises with image quality the further away from the box speed you get. Fortunately box speeds on films are only recommended values, that when the film is developed as standard the negatives will reach a specific density and contrast. The density and contrast will change with each stop you diverge from the recommended value, if you keep your expectations to modest levels you will get something usable. I've seen people push T-max 400 to 6400 and complain that their images looked like they were shot in a snowstorm....

11-07-2018, 04:01 AM   #5
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QuoteOriginally posted by Digitalis Quote
Negative films are pretty forgiving
This is a useful overview of Portra 400 latitude.
11-10-2018, 08:55 AM   #6
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With the latitude of Portra 400, an exposure index of EI 500 is pretty much unnecessary and a moot point. That said, you can extrapolate the development time increase needed from the following Jobo C-41 Press Kit instructions on the subject of push processing:

1-Stop Push: Increase development time by a 1.25X factor
2-Stop Push: Increase development time by a 1.5X factor

EDIT: For EI 640 I'd just round to EI 800 and push 1-Stop.

Last edited by tuco; 11-10-2018 at 10:12 AM. Reason: Add Info
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