B&W Reversal: what is it with Ilford's hypo quantities?

iandvaag said:

PS - I know you said Ilford films, but I've also had success with Rollei Superpan 200 (aka Rollei IR 400 aka Rollei Retro 400s). The contrast is very high, but the film base is clear and it looks really good. Development time for EI 200 (or approximately EI 6 - 12 with Hoya R72 IR filter) is 6 min at 20C using D67.

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Thank you for your very helpful and encouraging reply! I will certainly refer to it as a guide for development times when I try using D168 (bearing in mind the lack of restrainer compared to D67).

As it happens, now that I've used up the Ilford films I had, I have four remaining films in my fridge - two rolls each of Rollei Retro 80S and 400S! I haven't tried using any Rollei yet but I've only heard good things about how they perform in reversal.

Last reversal I did was with FP4+. I was quite satisfied with the result from following the Ilford instructions, but whith NO HYPO at all. I exposed at ISO 100.

(You may find that the permanganate concentration is too strong for the Rollei films.)

Rudeofus said:

Lowering Dmax will not reduce contrast, it will only lower total dynamic range.

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This is true.
Take a look at these curves I've measured for Superpan 200 in D67 at 20 oC.
With a developing time of 6 min, the Dmax is 2.83 and the straight line gamma is 2.5.
With a developing time of 12 min, Dmax is only 2.34, but straight line gamma has increased to 3.0.

Well I've had rather more luck with a couple of rolls. First was HP5+ which I developed with the Ilford recipe but with no hypo at all. Somehow I had incomplete bleaching on a few frames which I've never had before which is odd, and I also stupidly exposed the film not immersed in water which I've also never done before (I don't know why I was being inconsistent) resulting in some droplet marks. Example:

The second roll was a film I haven't used before – Rollei Retro 400S. I also bit the bullet and made up a batch of Kodak D168 and D158 developers. Therefore this processing was quite a shot in the dark because it was an unknown film and an unknown developer. I used the starting recommendation from Ian Grant (who posted those formulae on here a while back, here https://www.photrio.com/forum/resources/kodak-b-w-reversal-processing-formulae.191/) of D168 undiluted for 6 mins at 20C for first development. They're not perfect but I'm very pleased with how they've turned out. Massive contrast as a combination of the Retro 400S's tendencies, the high contrast lighting (in the cat photos), and presumably also the short, very active first development. Here are a couple of examples.




Can anyone familiar with this film tell me if this is the normal kind of contrast to expect? Next time I might try diluting the D168 1:1 (as the recipe says you can) and using maybe 9 minutes of development. Next thing is to try the D168 with some Ilford films...I'm definitely not going back to using Ilford PQ Universal, and even more definitely never putting any hypo in my first developer again. The D168 has 2g/L of potassium thiocyanate, incidentally.

There is no correct/incorrect contrast in B&W reversal processing, there are only slides which match your expectation/ambition - or not. E6 color slide process is a standard process, which works the same across a whole range of different film brands, whereas with B&W reversal processing you are basically on your own. On the plus side you don't have to worry about balancing of three color channels, so you can easily exploit more degrees of freedom to get the look you want.

The "incomplete bleaching" you write about could well be too low fog level in first dev step, translating into gray highlights, exactly the thing you would expect if you leave out the solvent. I recommend you increase/decrease development time until contrast is where you want it, then increase solvent in first developer until the highlights are clear, finally add Bromide until the blacks are where you want them.