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  1. #1

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    Does my Nikon 50mm f/1.4 AI lens need a CLA?

    My lens when I turn it all the way to the right should be focused well at infinity, but I have to turn it back about 2mm for it to be completely sharp. Is this normal, or do I need to get it repaired. Thanks

  2. #2
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    That particular lens should be sharply focused at infinity when the focus ring hits the stop. However, it is not uncommon for a lens to be designed to focus beyond infinity, as your lens apparently does, to compensate for thermal expansion. If the lens operates properly in all other respects, I would not send it in for a CLA.
    —Eric

  3. #3

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    Quote Originally Posted by jayel View Post
    My lens when I turn it all the way to the right should be focused well at infinity, but I have to turn it back about 2mm for it to be completely sharp. Is this normal, or do I need to get it repaired. Thanks
    Do you have other lenses which line up at infinity on that body? because it could be the body; a misaligned mirror, an improperly seated screen, or missing shims under the lensmount could all cause this. 2mm sounds like too much.

  4. #4

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    I think there will only be a problem if the lens did not go right to infinity, going past is not a problem.

    Some Olympus lenses I used many years ago were sent to be adjusted because they did not focus right at infinity. I never knew the cause but after adjustment they worked perfectly.

  5. #5

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    Quote Originally Posted by BMbikerider View Post
    I think there will only be a problem if the lens did not go right to infinity, going past is not a problem.
    Some Olympus lenses I used many years ago were sent to be adjusted because they did not focus right at infinity. I never knew the cause but after adjustment they worked perfectly.
    I've never seen or heard of a Nikkor (or any other lens) going that far past infinity.

  6. #6

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    What is past infinity? Please answer using engineering terms, not metaphorical psychobabble.

  7. #7

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    Many years ago I took apart a Nikkor 50mm 1.4 non-AI lens to clean it, and if my memory serves me well, there was a stop built-in to the lens so that the focus ring stopped at infinity. Perhaps the AI version is similar, and the stop is chipped or bent so that the focus ring goes too far.

    The infinity stop on all of the manual focus ai or ais lenses I have is built in to the lens, so unless the rear element hits something as it recedes to the infinity position, there should not be an issue with the body. If the rear element hits something, the focus ring will not go far enough to reach the infinity setting, so this does not apply to you, as your lens goes too far.

    By the way, my 300-mm 2.8 AIS ED goes about 7 mm past infinity and this is normal, to allow for thermal expansion (it is internal focus, and 7 mm is not that much compared to how far the focus ring turns for the full-focus range).

  8. #8

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    Quote Originally Posted by BrianShaw View Post
    What is past infinity? Please answer using engineering terms, not metaphorical psychobabble.
    When the index is set at infinity, the lens is "past" infinity (lens closer than it's infinity focus) and the index has to be set at a closer distance to bring an "infinite" (say the moon) object into focus. Sounds like the OPs lens needs to be set around 20 meters to focus at infinity.

  9. #9

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    Quote Originally Posted by E. von Hoegh View Post
    When the index is set at infinity, the lens is "past" infinity (lens closer than it's infinity focus) and the index has to be set at a closer distance to bring an "infinite" (say the moon) object into focus. Sounds like the OPs lens needs to be set around 20 meters to focus at infinity.
    Ahh. I got sidetracked I guess and was wondering how far (mm, inches, yards, kilometers) past infinity "past infinity" was.

    Like you said earlier... I've never seen nor heard of a Nikkor that didn't stop at the infinity index mark. Something wrong with that lens probably. If the infinity index is offset, I wonder if the others are equally offset.

  10. #10

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    Does the focus ring stop at the infinity mark, or as I assumed, go past it?

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