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  1. #1

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    Hello, APUG'ers!

    In my possession I now have a Jobo drum (forgtot which modei it is). Anyway. it takes 5 pieces 4x5 sheets and consumes 300ml developer. I have a rollerbase for it.

    My question is what kind of rotation is required?
    Henning Jansen
    Stavanger - Norway

  2. #2

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    round and round...

    sorry...


  3. #3

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    Nige is wrong-)) It's a little one way. Then back the other way-)) If your base doesn't change directions then I think you're supposed to lift the drum up and fip it end over end every so often.

  4. #4

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    Quote Originally Posted by Nige
    round and round...

    sorry...


    ;-/ Ahhh.... suddenly it all became obvious. The rotation is ... round. Didn't think of that.!

    Anyone with an idea on what frequency - how many rotations per minute or second?
    Henning Jansen
    Stavanger - Norway

  5. #5
    Ed Sukach's Avatar
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    [/quote]
    ;-/ Ahhh.... suddenly it all became obvious. The rotation is ... round. Didn't think of that.!
    Anyone with an idea on what frequency - how many rotations per minute or second?[/quote]

    You apparently have one of the "3000" series tanks. According to the JOBO instruction manual for the CPP2, using a 3000 series tank, with 4" x 5" film, the rotation should be set at "F". I've never timed the frequency, but all I ever use with either 35mm or 120 film is "P" - which, if memory serves is about 75 RPM - or would be if the rotation did not reverse itself every two(2) revolutions. "F" is the slowest rotational speed available - and I am going to guess at about 30 RPM ... If it was "one way" ... etc. - see previous.

    There is one instance - with 110 film - where JOBO does NOT recommend reversing rotation - and suggests that the reversing cam be "switched out of the way" so that the drum revolves in only one direction.

    Now - my opinion, for what it is worth: I have an idea that the rotation, like the agitation of a hand-held tank, is not really all that critical. I'd start at about 30 RPM, and increase the rotation speed if I detected uneven development.
    Carpe erratum!!

    Ed Sukach, FFP.

  6. #6

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    [/quote]
    Anyone with an idea on what frequency - how many rotations per minute or second?[/quote]

    My Jobo CPE2 Plus rotates at 75 rpm and has bi-directional rotation. I have used the hand roller before the CPE and I just used a constant slide of the hand for 10 pushes one way they reversed the hand movement for 10 pushes the other. I used a 60 second pre-soak and stuck to the development times for inversion processing in a small tank.

    I got good results and really strong wrists.

    Mike

  7. #7
    galyons's Avatar
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    I use a Jobo CPP2 with both Expert (4X5) and 2500 series (MF). For B&W, I like ABC+ Pyro. Lowest rotation speed is about 22, I shoot for 25+/-. Formerly I used a CPE-2+. One speed 75. Quite honestly, I see little difference, if any at all, on the MF work between the two speeds.

    Cheers,
    Geary

  8. #8

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    Quote Originally Posted by Ed Sukach

    Now - my opinion, for what it is worth: I have an idea that the rotation, like the agitation of a hand-held tank, is not really all that critical. I'd start at about 30 RPM, and increase the rotation speed if I detected uneven development.
    Does this depend on the amount of developer in the tank? If somebody was using the bare min I'm thinking everything is more critcal.

  9. #9

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    I'm also wondering why people don't like the 2500 tanks for 4x5?

  10. #10
    Ed Sukach's Avatar
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    Quote Originally Posted by Robert
    Quote Originally Posted by Ed Sukach

    Now - my opinion, for what it is worth: I have an idea that the rotation, like the agitation of a hand-held tank, is not really all that critical. I'd start at about 30 RPM, and increase the rotation speed if I detected uneven development.
    Does this depend on the amount of developer in the tank? If somebody was using the bare min I'm thinking everything is more critcal.
    I don't think so. The idea of rotation is to take the place of agitation, and to prresent "fresh" or relatively so - chemicals to each individual area of the media.

    There are minumum amounts of solutions needed to "cover" in processing - whether or not they are sufficient for processing is another consideration - but I don't think there is much of a link between the amount of chemicals and the rate of rotation/ agitation.
    Carpe erratum!!

    Ed Sukach, FFP.

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