View Full Version : Rotary processing and compensating development

James Phillips
24-Feb-2002, 10:25
I am just finishing preparing a bit of information on using Unicolor drums for n egative development and a thought occurred to me. If a person wanted to do ?comp ensating development? by permitting the negative to remain still (un-agitated) i n the developer then using a rotary processor such as a Unidrum or a Jobo would not be acceptable. Would this be a correct assumption?

For anybody who is interested in Unidrum processing of negatives you may want to look on my temporary site. http://www.telusplanet.net/public/dwd/drum.html (l ots of pictures so be patient)

As a side bar the above content will only be there for a short while as I use my small amount of web space for many things. If anybody has a web site and feels that the content on the Unidrum may be useful to others then I offer them to fre ely copy any or all of the content and place it on any site of your choice.

Douglas Gould
24-Feb-2002, 12:05

I hope someone finds a permanent home for that site. Your explaination was great for a beginner like me. Exactly some of the answers I was looking for.

I take it that with the unicolor drums, all the chemicals can be dispensed in and out of the drum through a light tight lid? Rather than the "load & close in the dark" method that BTZS requires. That sounds really good to me.

William Marderness
24-Feb-2002, 14:37
I have done many tests with Jobo processing. Compensating development means you get high shadow contrast and low highlight contrast. Instead of a straight line curve, you get a shoulder (lower contrast) in the highlights. This can be achieved with a Jobo by using D-23. I have plotted the curve of D-23 straight, 1:1, and 2-bath in a Jobo and you do get this type of curve. Using D-23 straight, diluted, or with 2 baths did not change the curve shape.

mark lindsey
24-Feb-2002, 22:48
I believe that I heard that John Sexton still uses tray dev. for extreme dilute developer work

Jim Chinn
25-Feb-2002, 00:23
Rotary processing is great for most needs. I process about 70% of my negs in a JOBO. But the rest is tray processed, as is all my 8x10 negs. Like everything else in photography no one chemical, process or camera is going to work for every need.

William Marderness
25-Feb-2002, 04:24
A Jobo works for compensating development. Use D-23, and you will get high shadow contrast and low highlight contrasts. It works.

25-Feb-2002, 12:02
James, I've created a new website called:


I've mirrored your article, and it's there for everyone to enjoy! :-)

If anyone else has anything LF related that they'd like to post but don't have the space, let me know. I don't have a ton of bandwidth, but I should have enough to post stuff like this.



N Dhananjay
25-Feb-2002, 17:03
As folks have mentioned, D23 is a developer that does provide a shoulder on most film curves - primarily due to the sole developing agent, Metol which has an ability to develop shadow detail quickly but has trouble building density.

However, you are correct in saying that reduced agitation also achieves a similar effect - in fact, it is the only reliable method I have found useful for any particular film-developer combination. Said another way, you could develop using D23 and minimal agitation in a tray and you will get even greater compensation (greater shadow contrast and a shoulder) than you do with D23 and continuous agitation.

Cheers, DJ

mark lindsey
25-Feb-2002, 19:57
its reduced agitation plus a highly dilute developer that is most useful for extreme compression

Jim Kish
27-Feb-2002, 14:30
Mark is correct, Sexton has a really really nice Jobo setup, but uses a nifty homebrew gadget called a "slosher" to tray develop negatives when compensating development is required. I'm sure a Jobo could do the trick, but it may take some extra fine-tuning.

Jorge Gasteazoro
27-Feb-2002, 15:56
The "slosher" can be bought at Summitek (www.summitek.com). ALthough I also use the Jobo drums, I have this gizmo also, it is great for tray developing more than one negative.