Very, very faint density streaks in Jobo Expert drums..
Therefore I am back to tray processing for all important negs...
Too bad, I liked the Expert drums!
You may be experiencing something Jobo refers to as "Road Ruts" . If you talk to a technician they may be able to give you suggestions to minimize the possibility of uneven developement. I talked to a tech. that ultimately admitted that it was an issue they never solved.
In any case, what worked for me was slowing the rotation speed to 50, and eliminating the pre-wash. Although it would seem a pre-wash would assist in even development, doing away with it helped for some reason.
And eventhough the expert drums have a physical capacity to take x amout of film, lowering the film volume may help. (For example: 6 sheets of 4x5 max and the full 1000 ml. )
Have a look at this thread, it may give you some ideas:
good luck, cameron
The posts that you linked to were very interesting.
I use an expert drum and use it exclusively with pyro type developers.
which need a presoak, even in trays. These developers are great when it comes to separating very high values. And it is in these high values I see the problems.
I use 1000ml always. My tank is level. I use all kinds of 5X7 sheet film. Unfortunately the negs are not as even as when I process by hand in trays.
Again, too bad - developing sheet film in daylight is (WAS!) great.
Thanks for your help.
You might PM Sandy King and get his recommendations on a pyro developer to use in Jobo tubes. He is the real expert on this topic. I know that he has written several posts on APUG about the routine he uses with Jobo tubes with pyro developers.
Per, the only problem I've had with tube type development was due to rotational speeds which were too fast. It ends up making thin streaks which appear as to be density artifacts on the film. Can you slow things down to a minimum, then try again? This was the problem I had, and was easily solved once I found the cause (me). I still use a pre-soak in all of my films with pyro developers. Best, tim
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We experienced *Road Ruts* that would show as faint minus density in the print.
Basically we tried everything: The solution. take the drum off the motor after the first rotation, Agitate as you would with a stainless steel tank, put on for one rotation , take off and agitate as before , put back on motar and proceed.
This definately solved the problem and we use this method all the time.
We never saw this with an expert drum, but with a full run of 120 film .
This problem was mind boggling, and trying to solve with techniques on the machine only did not solve the problem.
Hello Per. With PMK and it's derivatives I never did solve my issues even with tray develpment. The extra density along the edges with tray dev. 1 at a time seemed worse than the JOBO to me. PyrocatHD solved 99% of my dev. issues. And yes, I run the JOBO at it's slowest possible speed right where the knob clicks it on. With 12X20 I learned I had to jostle the entire machine back and forth a bit to move the dev around but that wasn't with an expert drum, but with the 20X24 print drum.
I don't have a warranty left to void, so I'll tell you my method. I use 2500 and 1500 series drums for roll films, with the magnetic drive. I removed the magnet, made a tiny groove in the mounting hole and put in a thin plastic shim. So the magnet is not longer perfectly perpendicular to the drive shaft, and the tanks "wobble" a little bit as they rotate. More wear on the roller blocks, but no more density differences. Anyone thinking about doing this, the operative word here is tiny- you only need a SMALL amount of angle for this to work. Too much and your tanks will be banging into the machine like a rotary hammer. Bob Carnie has offered a good solution for cog-drive users.