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Thread: Manual Focusing when Autofocusing

  1. #1

    Default Manual Focusing when Autofocusing

    Will damage be done to a lens (say a Sigma 75-300mm f/4.5-5.6 or EFS 18-55mm) that changes its length when focusing if I were to turn the focus ring while the lens is in the middle of a autofocus operation? Is there a difference whether the lens has FTM feature(any damage if manually focusing while lens is still autofocusing?
    Last edited by theNoobiestNoob; 17th December 2005 at 10:12 PM.

  2. #2

    Default Re: Manual Focusing when Autofocusing

    not for Canon lenses........they have a AF/MF select switch..... when its switched at AF, the MF is disengaged from the manual focus ring so u will not interfere with/against the AF mechanism's focusing preferences

  3. #3
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    Default Re: Manual Focusing when Autofocusing

    For Nikon's AF-S, there is true FTM, where even after the AF has locked focus, the user can just turn the focus ring to refocus without the need to touch any switch. This does not damage the lens at all. But only AF-S. The older AF-D needs you to disengage the focusing.

  4. #4

    Default Re: Manual Focusing when Autofocusing

    Quote Originally Posted by Watcher
    For Nikon's AF-S, there is true FTM, where even after the AF has locked focus, the user can just turn the focus ring to refocus without the need to touch any switch.
    Actually true FTM refers to the ability to adjust AF at any point in time, even during focusing and this is allowed by most AFS lenses.

    Others like Sigma HSM allows adjustment only after AF is locked.

  5. #5

    Default Re: Manual Focusing when Autofocusing

    Canon Ring-type USM allows for FTM

  6. #6

    Default Re: Manual Focusing when Autofocusing

    Quote Originally Posted by user111
    Canon Ring-type USM allows for FTM
    Not sure about canon, but does it allow manual focus override even in the midst of AF acquisition?(i.e before AF is locked)

    So far, only nikon AFS(except for the 18-55/55-200) and Minolta SSM lenses offer this feature. Sigma HSM requires AF to be locked before the focus ring takes effect.

  7. #7

    Default Re: Manual Focusing when Autofocusing

    you can turn the focussing ring anytime without side effects

    that itself will qualify for the right to the term "FTM"

  8. #8

    Default Re: Manual Focusing when Autofocusing

    Anybody know about ZD lenses?
    <<To be updated>> / Vivitar S1 70-210 f3.5

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