LPL 7700 Pro Enlarger Light Falloff for MF negs. Help!

Discussion in 'Darkroom Equipment' started by Thanasis, Sep 7, 2008.

  1. Thanasis

    Thanasis Member

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    Hi,

    I was doing some printing of 6x6 B&W negs with an LPL 7700 Pro enlarger with a Schneider 80mm enlarger lens. I noticed fairly significant light fall off in the corners of my prints. The negative density looks pretty constant all the way across so I am pretty sure that it is not the negative that is causing the problem.

    I have not used this enlarger for 6x6 MF before but I was using it for 35mm (with a 50mm lens) with no problems before i simply switched lenses and neg carriers. Is there anything else that I should have adjusted on the enlarger in order to set it up for 6x6? I suspect there may be something else but without a manual I can't be sure. Can anyone help?

    Please don't suggest burning in the corners. I am looking for responses that positively address the enlarger configuration. I want to make sure my set up is correct before I resort to "work-around" measures.

    Thanks and regards,
    Thanasis.
     
  2. Jeff L

    Jeff L Subscriber

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    I bet the issue is the light diffusion chamber inside the head. In my Rollei Nikor (LPL) it had a styrofoam chamber that is meant for 35mm. I removed it and lined the area instead with thin (1/4") styro that I cut myself. It's really very easy and my prints were very even. I tested my modification by exposing a sheet of paper with no neg and exposing it just long enough to be gray. I could then look at it to determine that the mod was doing what I needed. How this explains it clearly enough.
    Jeff
     
  3. ozphoto

    ozphoto Subscriber

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    I use a 105mm lens with the same enlarger and neg size. Don't have any problems with this configuration.
    Nanette
     
  4. Thanasis

    Thanasis Member

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    Do you know if you need to adjust the condenser lenses in the head when going from 35mm to MF?
     
  5. ozphoto

    ozphoto Subscriber

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    No, I've never done that. I do have to invert the lens ring when I swap from 35mm though, otherwise I can't get it to focus.
     
  6. Thanasis

    Thanasis Member

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    Just to prove that you really can find anything on the internet (albeit in a foreign language) i present the following:

    http://manuelsphoto.free.fr/lpl7700pronbp4.jpg

    At the top of the page it seems to say (with the help of online French-to-English translator) that condenser no. 3 (uppermost) is required only for focal distances of 50mm and lower and that for focal distances greater than 50mm only condensers No.1 (presumably the lowest one in the stack) and No.2 (the one above the filter drawer) are required.

    I'm going to give this a go sometime this week and I'll let you know how it goes.

    regards,
    Thanasis
     
  7. Jon Shiu

    Jon Shiu Subscriber

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    Yes, and if you slide up the front cover, there is a diagram on the back of it.

    Jon
     
  8. Thanasis

    Thanasis Member

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    Really? I'll have to check. I am using a hired darkroom so I will try to have a look this week. Thanks very much for the info Jon. And thanks to all who gave advice/suggestions/help.

    Regards,
    Thanasis.
     
  9. dancqu

    dancqu Member

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    My instructions for the Omega B8 also leave the
    impression that a third condenser is Required for
    smaller formats. That is not the true.

    The two larger, lower condensers will cover all
    formats. Actually the third condenser is an 'extra'
    at no additional charge. The further condensation
    of the light beam provided by the third condenser
    allows for more reasonable exposure times when
    making large prints from small negatives. Dan
     
  10. Jon Shiu

    Jon Shiu Subscriber

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    re: the LPL enlarger, I believe the light bulb is also adjustable in position and rotation for more even results.

    Jon
     
  11. ath

    ath Member

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    In my LPL I removed the third condensor lens for 35mm; without the third lens it turned out to be brighter (!).