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  1. #1
    fred's Avatar
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    difference CPE2 and small tank developing times

    Is there a relation between developing times of f.e. a Jobo CPE2 with constant agitation and a classic small tank (for the same combo film/developer)?

    And if so... it is a linear relation? Is this relation the same for a N-3 as for a N+2 times?

    And what is this relation?


    Many thanks for your answers!
    Fred

  2. #2
    L Gebhardt's Avatar
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    I have heard it is 20%, though I also changed temperature when I started using a Jobo, so my time were about 40% shorter.

  3. #3
    fred's Avatar
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    Quote Originally Posted by L Gebhardt
    I have heard it is 20%, though I also changed temperature when I started using a Jobo, so my time were about 40% shorter.
    Thanks Gebhardt,

    Analysing and comparing figures for x-tol and tri-x roll film for example, there is no linear/constant relation between the two lists.

    for trix-x 6049 its going from 1.34 over 1.29 to 1.36
    but
    for tri-x 6043 it's going from 1.35 to 1.17

    So wondering which formulas are applied?

    And wether these formulas counts for every combo film-developer?

    Fred

  4. #4

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    No, there is not a linear relationship, as Jobo's research discovered. They found, however, that if you add a 5 minute presoak with tempered water, development in the Jobo should be very close to the times listed for classic small tank inversion development, that's assuming of course that the listed times are accurate.

    Make sure to use a good termometer in your developer solution with your Jobo. You will probably have to set your Jobo's temp to slightly higher than your process calls for to get the right temperture in the developer, which is what is important.

  5. #5
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    I used that recommended 5 minute presoak and I still found that I had to cut my times by around 30%. I finally went back to using SS invertables because I just didn't feel that I could hold down the contrast with constant agitation.
    That is called grain. It is supposed to be there.
    =Neal W.=

  6. #6

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    Quote Originally Posted by Flotsam
    I used that recommended 5 minute presoak and I still found that I had to cut my times by around 30%. I finally went back to using SS invertables because I just didn't feel that I could hold down the contrast with constant agitation.
    Try diluting the developer, and/or using a shorter time. As long as the time is greater than 5 minutes, you shouldn't have any problems. If you dilute the developer, remember to use enough to get consistent development. With d76 and xtol, just two examples, you should use at least 100ml of stock solution per 36 exp. roll of 35mm film, or equivalent.

  7. #7
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    I changed my dilution of HC110 from 1:32 to 1:50 and decreased my time approx 10% with TX400 and the T-max films. They seem to print well at grade 3 on multigrade IV.
    John Harvey
    Colorado Springs, CO
    harveyje@usa.net

  8. #8
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    This is very interesting. I have just been given a Jobo CPE2 and was considering developing my B&W, especially the pushed films because of the time involved. I use HP5 at 3200 or 1600 in Ilfotec normally which is, off the top of my head, 16 minutes in a small tank. In your humble opinions, is it worth using the Jobo for this?
    [size=1]the all new darkplanet photoblog[/size][size=1]
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  9. #9
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    Quote Originally Posted by Peter De Smidt
    Try diluting the developer, and/or using a shorter time
    Coincidentally, I did experiment with diluting my developer. I didn't think about it helping with contrast but wanted to lengthen my times which were uncomfortably short due to the constant agitation. It worked fine for that.

    I just believe that those rests in intermitant agitation are important to keeping contrast in control.
    That is called grain. It is supposed to be there.
    =Neal W.=

  10. #10

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    Quote Originally Posted by Flotsam
    Coincidentally, I did experiment with diluting my developer. I didn't think about it helping with contrast but wanted to lengthen my times which were uncomfortably short due to the constant agitation. It worked fine for that.

    I just believe that those rests in intermitant agitation are important to keeping contrast in control.
    I don't understand this. I routinely develop TMX and TMY from N-2 to N+3 in a Jobo. There's no problem with doing this.

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