Tetenal C41 with JOBO ATL and 8x10 Expertdrum

Hello,
I have been using Tetenals C41 with my JOBO ATL 2 on 8x10 negatives. I have been seeing some uneven development lately. I use the recommended times from Tetenal and the chemical are fresh and "one shot" only. I use the Expertdrum that is supposed to be excellent for this. I also use the chemical volume recommended by JOBO for this drum (8x10" = 4,2 SU x 30 ml) 126 ml for each 8x10". What can help to avoid this problem? Pre-wetting, using distilled water in the developer? Any tips would be grateful. I have uploaded a jpg file to show the problems, I used levels in Photoshop to exaggerate the unevenness.

Thanks

Hi SinarP2,

Yes, I have had that problem, and it is because the drum is not level. Leveling your ATL machine nor adding more chemistry will not help. You must level the drum. I used a short level and put two small magnets of equal thickness on each end of the level so that they rest directly on the outer surface of the drum and then shim the ATL so the drum is level.

I use three different types of drums for the three formats I shoot. I have multiple of each drum type and each type of drum levels out differently. I have made a set of standard shims for each drum type, and as I switch drums types I switch shims.

You must also have plum lines on your drum so that when you put the drum cover on the drum does not wabble as it rotates. To do this keep putting the drum cover on and rotating it on your ATL machine. When the drum rotates smoothly without wobbling use a Sharpie marker to trace a plum line around the drum cover on the drum. Once you have done this, you can pound the drum cover to line up with the trace line to illiminate any wobble.

Hope this helps...

Thanks Steve,

I will check this next time I develop and I will let you know how it goes. Its a strange unevenness looks more like chemicals has been running over it like someone has poured chemicals over the negative.

How about get some adjustment "feets" to "realign" the ATL for the drums?

Cheers