Neutrino
Over the weekend, I shot some Portra 800 at around ISO 1600–3200 due to the low light. I’d originally only planned for an exposure at ISO 1600, but there were some subjects that simply wouldn’t come out properly even at wide-open aperture, and I’d already reached the lower limit of what I could manage in terms of shutter speeds. So, out of necessity, I also performed some exposures at ISO 3200.
I’d like to develop the film over the next few days. I haven’t carried out any push processing with the Tetenal kit yet. The instructions say to add 30 seconds per stop. So far, so clear. However, I only develop at 30 degrees, as I find the whole process a bit more pleasant and you don’t have to work quite so precisely and under pressure. But what does push processing at 30 degrees actually look like? With standard development at 38 degrees, the time is 3 minutes 15 seconds, and at 30 degrees it’s 8 minutes. So it’s more than double. Without having worked it out precisely, I’d say that at 30 degrees, you can assume an approximate increase in development time of 1 minute 30 seconds per stop of push processing. Is my thinking correct, or can we forget about such an analogy? Is it perhaps only possible to push colour films effectively at higher temperatures? Final question: What do you think makes more sense – pushing to 1600 or to 3200? I would go for 3200. I’d like to scan the negatives and perhaps even attempt my first colour enlargement with them.
Photux
I also use the €30 process with Colortec, though mainly because my equipment is actually completely unsuitable for colour and the tolerances are (hopefully) greater over the longer exposure time. That said, I only develop colour film myself for experimental purposes (cross-processing, etc.).
I haven’t tried pushing it yet, but the extension factor per stop should be between 1.2 and 1.4. In that respect, you’re probably not far off with 1:30. If you want to be absolutely precise, you’d have to carry out tests under your exact conditions anyway, as the C41 process isn’t designed for push processing and not every film will behave exactly the same.
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In any case, I would only push by one stop, i.e. to 1600. Colour films in particular are actually quite tolerant of underexposure, but they really don’t like overexposure (I’m assuming here that the same applies to over- or underexposure). If you were to push to 3200, I’d be worried that it would only make matters worse.
Neutrino
Thanks for your reply. I’ll give 1 minute 30 seconds a go then. I hope something will come of it. I’m just waiting for a friend to arrive and then we’ll get started. =) I’ll let you know how it goes.
Photux
Go on, I'm curious! And good luck...
Neutrino
A few rolls of film have now gone through the scanner. Unfortunately, the film didn’t turn out quite as I’d hoped, but at least I got something. You never stop learning; hopefully it’ll be a bit better next time.
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We developed the film for ten minutes at exactly 30 degrees in a freshly prepared bath. So instead of the usual eight minutes, we took two minutes longer for the push processing. According to my theory, that probably corresponds to a push of just over one stop.
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Unfortunately, the film turned out a bit pale, at least the photos I exposed at ISO 1600. That surprises me a bit, because I’ve seen good results from a Portra 400 at ISO 3200 before. Shouldn’t an 800 film be able to keep up even better? Perhaps I should have pushed it even longer? The good thing is that, despite this, no photo is really unusable, even if the shadows are quite washed out in places.
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I also find the extremely heavy grain a bit of a shame. To my mind, these are really large grains. I must admit, however, that I’m a bit fussy in this regard. I love analogue photography, but unlike many others, I’m not a fan of pronounced grain. I prefer it smooth. Exceptions prove the rule, of course. I naturally assumed the film would be grainy, but this seems a bit excessive to me. I’ve seen much better results online. The coarse grain is, of course, partly down to the underexposure and overdevelopment, but I also suspect that the Tetenal kit generally produces a coarser grain than, say, a lab development? Could that be the case? The chemicals can’t really differ that much.
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Otherwise, I’m quite happy with it. =)
ThomasLoos
Colour films don’t have grain, but rather colour speckles – and they’re not as aesthetically pleasing as the black-and-white grain on an HP5 or TRI-X… at least in my opinion.
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The 800 Portra is, of course, more granular on the one hand, but comparatively fine for colour films in this category, so it’s no match for the (now defunct) Ferrania or the like… Pushing also doesn’t work nearly as well as with a black-and-white film, and areas of underexposure in particular are problematic when scanning C41 film, especially if the scanner tries to brighten up areas of underexposure somehow
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But perhaps you could show a few examples. I’ve already taken a few shots with the 800 Portra in quite poor light and find it actually quite good
Neutrino
Unfortunately, I’ve only just got round to finishing scanning the film today. I’ll tweak the photos a bit and post them here soon.
