PDA

View Full Version : Contrast issues with Paterson Orbital?



flycatcher
25-Jun-2013, 07:54
I process my sheet film on a Paterson Orbital tank - how_orbital (http://www.rogerandfrances.com/photoschool/ps%20how%20orbital.html)

Someone made a statement which I've reproduced here:

"With film in this processor you cannot get away with the 50 to 150ml of solutions and the constant agitation needed to keep the emulsion wet that works for prints. Constant agitation is no good for controlling contrast and tonal range. The amount of liquid to deploy in this processor with sheet films is 500ml."

Does anyone have an opinion on this? Should I figure out how to do development with minimal agitation to get better results?

Thanks
Arvind

Pete Watkins
26-Jun-2013, 00:10
I use 300 ml of solution and never have problems. I use D-76H 1-1, water stop and an Agfa neutral fixer (most of the time).
Pete.

Tim Meisburger
26-Jun-2013, 03:35
I use 70ml and never had a problem (that I knew about!). Maybe I should test some time. I use d-23 straight, acid stop, and plain hypo. I do know that if you use 500ml of liquid without cutting off the fins you can have problems with prints because the fins interrupt the intended flow of the liquid.

polyglot
26-Jun-2013, 04:12
caveat: I don't have an orbital.

My understanding is that with ~70mL and constant agitation, you get good uniform coverage of the film. If you stop agitating though, all the developer will pool in one corner and some of the film will be poking up in the air. If you put in 500mL, the film will be entirely covered even when not agitating.

The "constant agitation is no good" part indicates that the advice comes from someone who is partial to the usual once-a-minute agitation scheme as commonly used with roll-film. It tends to give a little better speed with more toe - a slightly different look. Some prefer it, some prefer the constant agitation. The point though is that if you stop agitating, you probably need more developer solution to cover the film.

If you use developers like Xtol, agitation doesn't make a huge difference. It does with Rodinal though: Rodinal with constant agitation looks quite different to Rodinal once a minute, which is again quite different to Rodinal stand development.

flycatcher
26-Jun-2013, 06:06
Thanks for the comments so far. I use HC110 in dilution B with 99 ml.

From the comments so far I gather that you'd get slightly diff highlights. Either you like it or not - provided you pour adequate fluid to submerge all films without rotation.

Can I take it that there will be no impact to the way shadows render?

Thanks.

Ed Bray
26-Jun-2013, 12:43
I used to use 400ml without the base and just gently rocked the Orbital gently for the agitation.

For Semi-stand I sit the Orbital without stand in a 10x12 tray of tempered water which is sat on a dish-warmer.

My Orbital's fins are still on and I have not noticed any issues with streaming.

cjbroadbent
26-Jun-2013, 13:51
... Either you like it or not - provided you pour adequate fluid to submerge all films without rotation. ...
No issues with HC110 and 150ml.
Plenty of issues with Rodinal - maybe it has to do with exhaustion.
Whatever the film, beware of sloshing more than 300ml around with the motor - it creates a wave that makes for uneven development (rather like the fins do when you use more than the prescribed 100ml).
Semi-stand in 500ml gives me under-developed ends. Perhaps stand needs level submersion. Anyway, for one-shot, single negative stand, a tray is more practical (if your bath/dark-room has a light-trap).

flycatcher
27-Jun-2013, 20:37
Thanks. Is it a good idea to do 85% time in case constant agitation is done?

I've heard that continuous agitation causes faster development.

orchardist
27-Jun-2013, 21:14
Echoing the comments above, I use the Patterson Orbital processor for 4x5 film. I tested my Ilford FP4 Plus film speed with its constant agitation and found that 15% reduction in the standard dev time gave me a good Zone VIII highlight value. The constant agitation gave me better consistency than a tank or even tray development (probably because I can be a bit of a day-dreamer during a long dev time.) I love my processor and wish I'd bought two when I had the opportunity, especially for the occasional 8x10 shoot.

I can't see how you would have a problem as long as you keep it moving, even when pouring in the chemistry. I hope it works as well for you.

polyglot
27-Jun-2013, 21:40
The time-reduction required when moving from per-minute to constant agitation seems to depend on the developer used. Xtol doesn't need much time reduction, Rodinal needs quite a bit of reduction.

flycatcher
28-Jun-2013, 07:31
It works reasonably well. So I thought, until I found until someone told me that I could be losing subtle contrast variations.

I use HC110 - which I believe is also somewhat sensitive to constant agitation.

Some of my recent pics here. - justtones.bligspot.com.

orchardist
28-Jun-2013, 08:16
I agree with polyglot - testing is the key, especially if you are knowledgeable about densitometry.

Paul H
1-Jul-2013, 03:19
I usually use PC-TEA in mine, at 1+50, and use around 150ml of developer solution. This does four 4x5 sheets without problems.

I have tried with more solution (like when using Rodinal), but found that using much more than 200ml lead to spillage.

I use it on the base and complete one wobbly revolution every 2 seconds or so, changing direction every 30 seconds. I've not noticed any uneven development or contrast problems.