sharpness problems with omega b22

Discussion in 'The Darkroom' started by mpap89, Jun 17, 2008.

  1. mpap89

    mpap89 TPF Noob!

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    So i just set up a darkroom with an omega b22 enlarger. its working ok. the main thing is that i can't get the edges of the prints to be crisp. i'm using my grain focuser to get the center sharp, but then the edges or the print aren't sharp at all. This seems likes something bigger than just alligning my enlarger, because its not sharp anywhere but the middle. Thanks
    Michael
     
  2. compur

    compur No longer a newbie, moving up!

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    What lens are you using?
     
  3. mpap89

    mpap89 TPF Noob!

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    its a saunders lpl 75 mm 3.5 lens
     
  4. compur

    compur No longer a newbie, moving up!

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    ... and what is the size of your negative and the aperture setting you are using on the lens?
     
  5. mpap89

    mpap89 TPF Noob!

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    2 1/4 negative at f22 mostly, but its still blurry in all apertures.
     
  6. Hertz van Rental

    Hertz van Rental TPF Noob!

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    There are a number of things that could be causing the problem so it's a matter of trial and error.
    I presume that the paper you are printing on is held flat in an easel.
    Is the sharpness only in the centre of the neg so that all the way around the centre is out of focus? Or is the sharpness in a linear zone running from one side of the neg to the other?
    If it is just sharp in the centre then check to make sure the negs are flat in the carrier.
    If the carrier sandwiches the neg between glass then that is not the problem.
    If the carrier is glassless or has only one sheet of glass then that could be the problem.
    6x6 negs are prone to buckling and when warmed in an enlarger can 'dome'. This means that the centre is on a different level to the edges and will cause your problem. The remedy is to get a carrier with glass.
    If your carrier does sandwich the neg between glass then the problem will be with either the condenser, the lens or a combination of both.
    First make sure the condensers are the right ones for your neg size and are fitted correctly - and see if any adjustments can be made to them or the light.
    If adjustments are possible then try playing around with them.
    If that doesn't work then it may well be the lens.
    Make sure you have the correct mount for the lens and that it is fitted properly.
    If that doesn't work then try using a different lens.

    If the zone of focus runs from one edge of the neg to the other then the problem is most likely to do with the enlarger surfaces not being parallel.
    The baseboard, lens plate, neg carrier and condensers should all be parallel. Some enlargers allow you to alter the angles of these (like on a studio large format camera) to adjust converging verticals.
    Often they don't go back square, or the stops aren't accurately positioned or they get knocked out with use.
    Check to ensure that all these surfaces are correctly aligned and that the light source goes directly through the centre axis.
    It is possible to get test negs with parallel lines and other markings on as an aid to setting up your enlarger. Some enlargers come with them.

    It is also worth checking the negs themselves using a magnifying glass to see if the edges are actually in focus.
    If all the negs were taken using the same camera then there is the possibility that the problem lies there.
    Try using a neg from a different camera to see if the problem persists.

    It's all a matter of elimination. Check one thing at a time and if you can't cure the problem come back here and tell us.
     

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