Adjusting development times for rotary proccessing

[photonsoup]

I will be processing some HP5 in a Jobo unit using HC110(b). The things I've read suggest developing for 15% less that the normal time for constant rotary development. Then I read to shorten the time by 15% if you plan on using an enlarger with a condenser, which I will be (either a Besler 45 or a Dust L1000).
Should I shorten the time by 30%? Or try something between 15% and 30%.
What has worked well for you in your experience?
Thanks
Bryan

[Leigh]

There are no hard-and-fast rules.

Everybody must calibrate the entire process, as Lord Ansel has explained.

Your optimum negative density depends entirely on how you render the final image.
That's unique to you... nobody else does it exactly the same way.

- Leigh

[richardman]

Yes, do some tests. Make some "well-exposed" negatives and start with 15% reduction, then see how they look to you. In addition:

1) It is claimed that if you do a pre-wash of 5 mins or so, no time reduction is needed.
2) Kodak also says that if you use Xtol, then no time reduction is needed with or without pre-wash.

For me personally, I just always pre-wash the film and forget about it. I'm sure some people will jump in and extol the eviliness of pre-washing, but it works for me. Try it and see if you like it.

[Leigh]

1) It is claimed that if you do a pre-wash of 5 mins or so, no time reduction is needed.

That's because the pre-wash saturates the emulsion, delaying the take-up of actual developer.

So you're still reducing the actual development time, just using a different method to achieve same.

- Leigh

[Peter De Smidt]

Note that Jobo's claim was that using a 5 minute pre-wash and times for inversion procession would get you in the ballpark, assuming that you have an accurate thermometer. A simple test would verify that.

[polyglot]

As above, it all depends. I've found that Xtol needs little or no reduction in time, Rodinal needs significant reduction in time. The effect of the prewash may or may not cancel out the increased development activity, depending on how concentrated your developer is and how long you develop for. I think prewashing has a bigger relative effect on high-concentration, short-time development approaches, and less effect on longer, higher-dilution developments. The effects also differ between films, not just between developers.

You will need to test, even if just briefly and approximately...

[AuditorOne]

I use continuous agitation quite a bit. For Kodak TMX100 I follow the manufacturer recommendation as I also use D76 as my developer. If I were to do something different I would have to experiment but results with other films (AEU400) indicate it wouldn't be far off.

This is AEU 400 shot at EI200 and developed in D76 1:1 for 10 minutes at 20C. Continuous rotation in a Jobo tank.

[Bruce Watson]

I will be processing some HP5 in a Jobo unit using HC110(b).

Actually, I'm thinking you won't be.

Years ago I tried mightily to get Tri-X to work with HC110 in a Jobo CPP2 with a 3010 tank. First at dilution B, then all the way to dilution H. HC110 is a very active developer, it really doesn't do rotary processing well. No matter what I did (within reason) I couldn't get my development times up above 5 minutes. I was always fighting excessively dense highlights.

I finally gave up and switched to XTOL. XTOL works great with rotary development. Not surprising since the R&D for it was done with rotary development.

I'm just sayin' to use HC110 in trays where it's happy. Use something else for rotary, something that likes that kind of continuous agitation.

[Ari]

Actually, I'm thinking you won't be.

Years ago I tried mightily to get Tri-X to work with HC110 in a Jobo CPP2 with a 3010 tank. First at dilution B, then all the way to dilution H. HC110 is a very active developer, it really doesn't do rotary processing well. No matter what I did (within reason) I couldn't get my development times up above 5 minutes. I was always fighting excessively dense highlights.

I finally gave up and switched to XTOL. XTOL works great with rotary development. Not surprising since the R&D for it was done with rotary development.

I'm just sayin' to use HC110 in trays where it's happy. Use something else for rotary, something that likes that kind of continuous agitation.

In contradistinction to this, I'll say that using HC-110 dilution H has always worked well for me, and rotary processing always comes out great.
I shoot FP4 and Acros, and a little HP5, so it may be that HC-110 in a rotary tank does not work well with Tri-X.

[Leigh]

HC110 is a very active developer, it really doesn't do rotary processing well.

using HC-110 dilution H has always worked well for me, and rotary processing always comes out great.

And here we have a perfect example of why each photographer must experiment and calibrate the entire process.

No two shooters will get the same results, even with (apparently) identical technique.

- Leigh