400 F5.6L Series Lens

Discussion in 'Digital Cameras' started by Don, Apr 30, 2004.

  1. Don

    Don Guest

    Folks, does anyone here have experience of the 400mm F5.6L lens with the
    1.4 EF teleconvertor? Do you maintain the autofocus on a 10D and if so is
    the autofocus degraded (speed wise). Also can you ascertain any real world
    degradation of optical performance.

    regards
     
    Don, Apr 30, 2004
    #1
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  2. A root 2 teleconverter loses one stop.
     
    Simon Gardner, Apr 30, 2004
    #2
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  3. This is incorrect. The 10D and most canon SLRs except
    top end models will only focus at f/5.6 and faster.
    So a f/5.6 lens plus a 1.4 TC =f/8. The camera will
    not autofocus.

    Some 3rd party TCs do not report to the camera correctly,
    so the camera will try and focus, but fail MOST of the time.
    I've tried on the 10D, D60 and Elans. The elans tended to do
    better. Even so the focus is slower and hunts for the
    best spot.
    see:
    http://clarkvision.com/imagedetail/relative-lens-sharpness
    for results with a 500 f/4 IS L with kenko pro 300 1.4 and 2x TCs.

    I also had some cheaper 3rd party TCs and my conclusion was I
    got the same sharrpness without a TC and just enlarging.
    Buy a quality TC. The Kenko pro 300 or Canon Tcs will be
    similar in quality. I've had no issues with the Kenkos.
    On my web site in the astro articles, you will see I do stacked
    2x + 1.4x TCs on the 500 and get excellent results.
    (also images in the birds gallery).

    Roger
    Photos, digital info at:
    http://clarkvision.com
     
    Roger N. Clark (change username to rnclark), Apr 30, 2004
    #3
  4. An f5.6 lens with a 1.4x extender becomes an f/8 lens. It won't
    autofocus on the 10D.

    -Dave
     
    Dave Herzstein, Apr 30, 2004
    #4
  5. Thanks. I tend not to use autofocus and plead unknowing ignorance.
     
    Simon Gardner, Apr 30, 2004
    #5
  6. Don

    Skip M Guest

    Then why did you answer?
     
    Skip M, Apr 30, 2004
    #6
  7. Don

    Alan D-W Guest

    A good point. Nothing worse than an inexpert who thinks he knows it all.
     
    Alan D-W, Apr 30, 2004
    #7
  8. Don

    Don Guest

    Thanks to those folk with an informed reply

    regard
    Don from Down Under
     
    Don, Apr 30, 2004
    #8
  9. Don

    Colm Guest

    Colm, May 1, 2004
    #9
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