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  1. #1

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    Enlarger lens - mount fit

    I purchase a used Chromega B enlarger a year or so ago. All has been pretty good except for bigger enlargements. So last night I decided to take things apart, re-align everything and give it all a good clean up. I discovered that the Nikkor lens cylinder is a bit smaller than the hole in the lens mount. This means that I cannot get the lens exactly in the center of the mount. Maybe this sounds dumb but is this a problem? Shouldn't the lens fit the mounting bracket snugly so there is no way to have the lens out of alignment. Of course I can use it after tightening the locking nut on the lens but I cannot be sure if it is actually centered.

    Also the lens itself has either tiny scratches or something inside the lens where I cannot get to it. So if I replace it do I need a correct fitting mount as well? It is a Nikkor 80mm

    Many thanks

    Ken

  2. #2

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    Hoosierken,
    I doubt that the play in the mount plate will be of any real consequence to you. The neg carrier or positioning of the negative in the carrier also lack precision, so unless there is a gross misalignment I wouldn't worry about it.

  3. #3

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    Hi Shaggy,

    Thanks for the quick answer. You're right, I hadn't considered that. Always good to have a second brain look at a problem.

    Looks like my real issue is a not so clear lens.

    Thanks again.

    Ken

  4. #4
    Bob F.'s Avatar
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    Internal aberrations to the lens are also unlikely to be a major problem as far as image quality goes. It is surprising how much you have to damage a lens before you can see a difference! If it is very dusty or the surfaces have been badly "cleaned" - i.e. multiple scratches - in its previous life however, then you may have a problem. Scratches on internal elements are unlikely so you may have fungus (thin threads, usually starting at the edge of the lens) or possibly dust from either the internal black paint or the diaphragm.

    Also possible is that the lens has been dismantled and incorrectly reassembled in the past. Look for slight damage to the indents used to take the lens spanner pins that would indicate that it has been unscrewed previously.

    It is usually easy to dismantle a lens if you have the correct adjustable lens spanner - just make sure you remember (this is a good use for a point & shoot digicam) the order and orientation of the bits as they come out. Dismantling the glued elements however is a different thing entirely...

    The Nikkor probably uses the usual 39mm thread so you should be able to score a correct lens mount from the auction site or somewhere else if you feel the need. Measure it across the threads to make sure.

    Good luck, Bob.



 

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