Help analysing results of Tri-X reversal, please
I need help understanding how to improve my first (successful) Tri-X reversal process test, please. I'm a bit hazy on how to think about the dev/exposure relationships within reversal processing.
I have run a test film strip of exposures on 35mm with 200ASA as the base and EVs of +1, 0 - 1.
The film was dev'd in strong Rodinal of 1:15 at 10 mins according to helpful suggestions from poster Tofek. The rest of the process was as the Foma Reversal Kit suggests. I reduced the Potassium Permanganate by 40% to help save the Tri-X emulsion from going too soft. (I am using the Foma kit to get started).
I cannot scan today but have photographed these on a light box. I think you can see the gist of the results. I can post close-up of each frame if needed.
I'm very happy and excited that I got a reasonable result but want to address the weaknesses of the process. What I am seeing is weak blacks and grey-looking hi-lights. An overall flatness. The -1 EV frame has the strongest contrast.
I'm guessing the exposure is OK - at least at EV 0 or -1. Is that right? The EV+1 seems to have no greys in the upper range.
Can adjusting the dev time improve the image and contrast? And if so which way?
Or do I just need to use a more vigorous, high contrast developer like Ilford PQ, for example. I guess I'm getting low contrast by using the TriX.
Is there another factor, I'm missing?
I may switch to D94 and mixing my own chems in the long run but at the moment I'd like to try and get what i have working to it's best advantage, if possible. I have Rodinal and Ilford PQ.
Last edited by mr.datsun; 02-03-2013 at 09:24 AM. Click to view previous post history.
That's quite grey as compared to what I get..The thing I sometimes do to increase contrast is to have the first developer at 24°C (adjust the time to the temperature, 7:15 for me) : in reversal process, Rodinal reacts nicely to changes in temperature in the 1st development. I've never tried touching the exposure though.
Huh sorry, I meant 6:45. Anyway, those times don't tell much, I change it everytime I do a test strip before developing the entire roll...the water must be changing quite often!!
But that makes me think I'm getting something wrong!
Originally Posted by Tofek
I just read, though, that in B&W reversal processing there's nothing much you can do about contrast. (Ilford, Reversal Processing 2003).
Can there be a key difference between Tri-X 35mm and Tri-X Super 8 that affects the result? (For anyone else reading, Tofek is using Super8 Tri X, I'm testing on 35mm before using Super8).
Another thing, should I have added Sodium Thiosulphate to the 1st developer? Doesn't this brighten the hilights?
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I think dilution affects the contrast too, but never tried it. With Rodinal I experienced a change in contrast linked with temperature (higher the temp, higher the contrast, with Orwo UN54 I got the same evolution). If you want to keep with Rodinal and the contrast is low, try higher temperature, like I already mentioned.
As for the halide solvents (KSCN or Na2S2O3), I was always told that with Tri-X they weren't needed. When I tried to add some to the 1st developer, it lowered the density overally so I decided not to use it. There's a huge debate on whether to use or not to use the silver halide solvents in first developer, so I guess you have to try and decide your own...
Thanks for the idea. I know with negative process all those things affect the way Rodinal works. More dilution = lower contrast., higher strength = more contrast. Here we were using 1:15 as per your suggestion and that so i guess that could be increased to 1:7, for example.
Still, as another test this evening I jumped in with both feet. Everything I read about reversal says use paper developer for it's more energetic nature, especially with lower contrast films like Tri-X. So I had just read the Ilford sheets on the subject and saw they recommended PQ at 1:5, 10 minutes. That's double the strength of using it for print and 3 times the strength of normal film processing. So I tried it at the suggested dilution and time.
The difference was dramatic and the proof is in the pudding. I think this digital photo of the strip taken from the lightbox has crunched the blacks a bit as, seen with the eye, there is still enough detail in there but the overall contrast and bite is a dramatic improvement. In my case the extra vigour of the paper dev has worked.
I think I could try a drop of sodium thiosulphite in the developer next to see if the hilights can be expanded a little more, too.
Very happy with the new test. Tomorrow I will scan the strips to get a better look and a sense of what a Super 8 sized crop will look like in terms of grain and detail.
Ilford PQ. 1:5, 10 minutes 1st and 5 minutes 2nd.
I think this single frame macro close up digital photo shows how lovely this slide looks:
Last edited by mr.datsun; 02-03-2013 at 06:07 PM. Click to view previous post history.
Tri-X has a reputation for not reversal processing very well, and the few times I have tried, that has also been my experience. The results are generally grayish, with poor contrast and gradation. The film base can also be annoying. Tuning the process will probably help, but I can't be encouraging. Kodak recommends TMax 100 for slides.
I've gotten great results from HC-110 and @ EI 3200, at high temp processing with some thiocyanate added to the mix.
n-west, thank-you for your comments and I note your reservations about this but I have to place what i am doing in context. These tests are a precursor to moving over to Tri-X Reversal Super 8. Without there being a dedicated off-the-shelf kit I wanted to run trials. That meant finding the right developer, dilution and timings to get a decent image before wasting precious Super-8 at nearly £20 a pop. So these 35mm slide tests are a dry run and I'm very encouraged by the last result. I actually like it!
Originally Posted by nworth
With regards the poor contrast and gradation - that's exactly what happened in Rodinal - poor contrast and flat areas with sudden changes from one grey tone to another - almost with a halo between them. I think the Ilford PQ has addressed those problems pretty well. There's some lovely tones in the new one and the gradations have arrived. It may not be perfect but it certainly has a look. I will post a proper scan later.
Also, as you mention the film-base – I'm guessing that the 35mm film base is contributing to the look of the results which is why I'm not too worried about proceeding to Super 8.
Last edited by mr.datsun; 02-04-2013 at 02:50 AM. Click to view previous post history.