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  1. #1

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    Mix-n-Match lens elements.

    Hi,

    Some what of a follow up question. In the process of getting a new Fuji 90mm, I actually won two 90mm SWD f5.6 lenses. Both lenses are nearly identical, the serial numbers are less than 250 units apart. One of them has has a slightly nicer front element and the other has a slightly nicer rear element. I was wondering if there were any problems taking the nicer elements and putting them together. They are the same exact lens with produced roughly at the same time, so I cant imagine any great differences between them. They seem virtually the same on GG, though the focus point changes by a millimeter or so.

    Any thoughts would be greatly appreciated.

    Thanx!

    Gary

  2. #2
    Ole
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    The wider the image angle and the shorter the focal length, the tighter are the tolerances.

    Instead of one slightly nicer lens and one slightly less nice, there is a very real risk that you could end up with two utterly crap lenses.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3

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    Quote Originally Posted by Ole
    The wider the image angle and the shorter the focal length, the tighter are the tolerances.

    Instead of one slightly nicer lens and one slightly less nice, there is a very real risk that you could end up with two utterly crap lenses.
    Even though the lenes are the exactly same with nearly identical serial numbers. could it be that much of a difference?

    Thanx!

    Gary

  4. #4
    Ole
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    Absolutely.

    Lens making may be a science, but the final assembly and testing is still an art.
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #5

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    Um, er, ah, it is an empirical question. Do the experiment. And report back on the results.

    You can always put the lenses back in their original states if the swap performs worse.

  6. #6

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    It is not that hard to find out. Take a photo that contains a great deal of detail with each of the combinatios. 1 each of the original (2) lenses. 1 with the proposed pretty combination and 1 with the proposed ugly sister. Take your photos wide open with an identifying note on the negative. Develop your negatives, put them into a glass carriera, raise your enlarger to its highest setting and make a 8x10 print of the center section and 1 of the corner for each negative.

    So, now, at least, you have a meaniful, if crude, way of determining how much change results.

    For the making of photos I would not become obsessive about the prettines of the lens. Pretty is as pretty does.
    Claire (Ms Anne Thrope is in the darkroom)

  7. #7

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    Quote Originally Posted by Dan Fromm
    Um, er, ah, it is an empirical question. Do the experiment. And report back on the results.

    You can always put the lenses back in their original states if the swap performs worse.
    That is something I planned on doing all along, just thought before I tried somebody might have some ideas. Thanx!

    Gary

  8. #8
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    When removing cells, watch closely for shims so you can restore the lenses to exactly their original configuration if necessary.

  9. #9

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    Well, I took a picture with each of the four possible combinations. They will be developed tonight and then scanned. Through the loupe on the GG, there is no discernible difference. All four combinations appear to be pretty much the same, only difference is a slight shift in focus of less than one millimeter. Even the lenses in the original configuration show a slight difference in focus.

    My guess is there will be no real difference between them. But I will wait until I scan and check the negs.

    Thanx Again!

    Gary



 

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