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chassis
1-Feb-2017, 11:10
Hello all

Getting ready to join the dark side of C-41 materials and process. I have some 4x5 Portra 400 and wondering what people are rating it for exposure? My practice for black and white is to liberally expose and tune the development to achieve desired contrast.

With C-41 being a standardized process, will the film deliver good results with 2 stops overexposure? In other words, does it tolerate EI 200? I have searched the internet and as always there is more information than can reasonably be consumed.

Good results to me means sufficient density for scanning and printing, maximum saturation the film is capable of, and manageable contrast for scanning and printing.

Thanks for any input.

locutus
1-Feb-2017, 11:56
I only have experience with Portra in 135 and 120 format, that being said; EI200 for Portra400 works well , however never ever underexpose Portra it just gets ugly very fast.

koraks
1-Feb-2017, 12:02
Agree on the advice not to underexpose, unless you want horrible, muddy, reddish shadows.
Also, EI200 is only a one stop pull. The film can handle that with ease. EI 100 would not be a problem likewise in virtually all conditions.

Mark Sampson
1-Feb-2017, 16:25
Chassis, rating a 400-speed film @200 is only one stop overexposure, not two as your post suggests. Any negative film, color or b/w, will easily tolerate one stop over. Given the differences between subjects, lighting, meters, and metering methods, your answer will only come from a exposure-bracket test. Color neg is more forgiving in exposure than transparency film, true, but do a test. Make the best print you can from each neg (contacts will do) and you'll have your answer.

chassis
1-Feb-2017, 19:01
Thanks for the comments folks. Agree 200 is one stop slower than box speed. Haven't had to think about EI for a while because I've been shooting nothing but Tri-X for a long time. Will give it a go at 200 and see what happens.

Larry Gebhardt
2-Feb-2017, 11:26
I've had good luck at 200, but I'm sure my metering system is not the same as yours.

Peter Gomena
2-Feb-2017, 11:45
I expose Portra 400 at EI 250, and Portra 160 at box speed. So far, so good.

agregov
2-Feb-2017, 16:57
I expose Portra 400 at 200 and Portra 160 at 100. That said, I think box speed for color films is usually pretty good. There a number of over/under exposure tests like this floating around which might help with a starting point: http://canadianfilmlab.com/2014/04/24/film-stock-and-exposure-comparisons-kodak-portra-and-fuji/

Serge S
2-Feb-2017, 17:12
I rate portra 400 @250
& portra 160 @100

ottluuk
5-Feb-2017, 10:19
Portra 400 @ 250
Portra 160 @ 125

On top of other things this makes it easy to reason about exposures with typical shutters marked ... 60, 125, 250, 500 ... in sunny 16 style (And yes I know the actual timings tend to deviate from the markings)

Bruce Watson
5-Feb-2017, 15:05
Getting ready to join the dark side of C-41 materials and process. I have some 4x5 Portra 400 and wondering what people are rating it for exposure?

I rate 5x4 Portra 400 at... 400. I've made plenty of tests, with relatively good precision. 400 is the sweet spot that gives me exactly the shadow detail I want, with no color shifting anywhere from black to white. It's what this film wants us to do.

The old saw "expose for the shadows and develop for the highlights" still applies. At least sorta, because this is a negative film. That is, expose for the shadows works. You just can't really do much of anything to develop for the highlights. Yes, you can perform a one stop push or pull, but it doesn't really buy you anything with C-41. Other than increasing the risks of color casts. Try it and see.

What you do get by throwing extra light at it (that is, by downrating it to, say, 200) is you increase the graininess. Is that what you really want?

chassis
8-Feb-2017, 18:03
Shot a frame today at 200, like the results. I will try with 400. I'm guessing it depends on the lighting, whether I will use 400 or 200. Low contrast lighting I will try 400.