jobo for developing 4 X 5 negatives

Regarding edge density and rotation speed, I processed my first batch of 4x5 film at the slow speed, and had problems with uneven development at the edges.
I Re-read the directions, and some posts here, and since I've used high speed with no problems. I have a CPE, and use the 2500 series tank.
The foamy developer pouring out at the end of the dev. time is disconcerting though.
I tried just doing inversion with the tank full a few times, works well, but it takes an awful lot of developer.

Consider a Phototherm. For routine processing it is easier to use than a Jobo CPE or CPP because Phototherm is fully automatic whereas the Jobo units are essentially enhanced manual units, even with the lift. The Phototherm also has some programability, mainly the ability to change the processing time for pushing and pulling, though it is not as flexible as the Jobo, again because Phototherm is automatic whereas Jobos are essentially enhanced manual units. (This comparison does not apply to the Jobo ATL series, which compete with Phototherm.)

One other thing: Phototherm parts, service, and new units, are still available from the manufacturer.

Funny- I always use the slowest rotation speed possible when processing in my Expert drum, using Pyrocat HD. I get very even, consistent results. I think it was in a post here or perhaps over on LF Info by Sandy King that recommended the slowest speed possible. In any case, it works just fine.

TheFlyingCamera said:

Funny- I always use the slowest rotation speed possible when processing in my Expert drum, using Pyrocat HD. I get very even, consistent results. I think it was in a post here or perhaps over on LF Info by Sandy King that recommended the slowest speed possible. In any case, it works just fine.

Click to expand...

Scott, I think it's a difference of tanks. The Expert tanks (3000-series) probably do well at lower speeds because the flow pattern of developer in and out of each tube is random. To the extent people see weird edge densities, it is with the tanks with reels, the 2500-series. In those, the constant agitation of the reels rotating through the developer can create patterns of turbulence that affect densities. I've never had a problem with it, processing 4x5s on the reels, but Melanie gets gutters on her 120 negatives processed on reels with the Jobo, e.g.:

http://www.mcnew.net/melanie/slides/02.html
http://www.mcnew.net/melanie/slides/04.html

But Melanie actually prefers the gutters for much of her work so she's not complaining. When she wants even development, she processes in conventional daytanks.

Melanie's experience has led me to avoid developing 120 and 35mm film in Jobo tanks -- I process them all by hand over the sink.

The difference in tanks also is relevant to the belief that rotation needs to be reversed. That might be true for the 2500-series (though I've not found it necessary when I process 4x5 sheets in them) but it is not at all true for the 3000-series tanks, again, because of the randomness of the flow in and out of each tube as it goes in and out of the developer.

Sanders

I'll vouch for getting overdevelopment along edges with 2500 series reels if the rotation in constant in one direction. There is a small plastic cam that switches the direction of the motor. Somehow (when cleaning the unit I think) I knocked the cam out of position and developed a couple of rolls of 120 with one direction spin. Sure enough, I had slight overdevelopment. But as long as the cam is in position and the rotation alternates, there is no problem with uneven development on the 2500 reels.

My 2551 tank and reels arrived. I had to practice a bit in the light loading the film, but developed 8 sheets and I'm really happy I bought the system. My roller is 40 rotations per minute, which I think is on the slow side, so just for the heck of it I turned the tank half way through for the developer and fixer. In any case, no uneven development (foma 200, microdol X stock, 8 minutes 20C). I was a bit nervous about loading the film, but it all worked out fine. I think my development time might be a little long, but that's nothing to do with the Jobo.