Function of clamp knob on the side of the Pentax FA 50 mm 2.8 macro lens

Discussion in 'Pentax' started by Ifan, Sep 8, 2004.

  1. Ifan

    Ifan Guest

    Can anyone tell me what the function is of the clamp knob on the side
    of the Pentax FA 50 mm 2.8 macro lens?
     
    Ifan, Sep 8, 2004
    #1
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  2. Ifan

    sgfan3 Guest

    Sounds like it is a focus lock.
     
    sgfan3, Sep 8, 2004
    #2
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  3. Ifan

    Bandicoot Guest

    It's because it's an AF lens that - being a macro - you might often want to
    use in manual focus. With the clamp off the focus has minimum drag so that
    the AF motor can focus it fast, with the clamp on there is a bit more drag
    so the manual focus feels better and more precise.

    Works pretty well, in my experience. The 100mm f 2.8 FA has something
    similar, as well as a focus rang limiter.


    Peter
     
    Bandicoot, Sep 8, 2004
    #3
  4. Ifan

    Ifan Guest

    Works pretty well, in my experience. The 100mm f 2.8 FA has something
    Thanks

    Ifan
     
    Ifan, Sep 9, 2004
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