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Thread: Confused on teleconverter and autofocus on a 7 or 70D

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    Default Confused on teleconverter and autofocus on a 7 or 70D

    Hi all,

    Per my other thread, I'm a little confused on how a 1.4 teleconverter would work on a longer lens.

    It's my understanding that a 600mm f.4 from Canon would work for the center focus point with a 1.4 teleconverter, but that this will not work on the 800mm f 5.7 on a 7 or 70D body.

    For those of you who bird, which is better? The 800 as it's slightly older can be found for a cheaper price, but I'm assuming it's still a very sharp lens? Or is the 600 with the 1.4 tele just as sharp if not sharper? Will be using it for just birds and wildlife, so trying to figure out the best way to go...currently leaning the 800 as it's less expensive used, but with the 1.4 tele is the 600 a better overall value?

    Thanks,
    Paul

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    All Canon bodies will support autofocus with all available focus points when used with f/5.6 lenses or faster. Thus, you would have the use of all AF points using the 600mm f/4 plus a 1.4x teleconverter with either the 7D or the 70D. For lenses slower than f/5.6 (e.g. 800mm f/5.6 + 1.4x), AF is only available on the 1D pro bodies or the 5D Mk III with the latest firmware but AF support is limited to the center focus point. With respect to your lens choice question, I would suggest you take a look at this : http://www.birdsasart-blog.com/2013/...e-winner-is-2/

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    Quote Originally Posted by Mike Milicia View Post
    All Canon bodies will support autofocus with all available focus points when used with f/5.6 lenses or faster. Thus, you would have the use of all AF points using the 600mm f/4 plus a 1.4x teleconverter with either the 7D or the 70D. For lenses slower than f/5.6 (e.g. 800mm f/5.6 + 1.4x), AF is only available on the 1D pro bodies or the 5D Mk III with the latest firmware but AF support is limited to the center focus point. With respect to your lens choice question, I would suggest you take a look at this : http://www.birdsasart-blog.com/2013/...e-winner-is-2/

    Yes, I read that. But then I read this: http://franzfoto.com/2013/02/18/cano...00mm-f5-6l-is/.

    This is a pretty tough decision...but I'm leaning a little toward the 800 as it does save me about $3500 new vs. used, and I also do not need a teleconverter. But I have a lot of thinking to do and hope to talk to someone at Adorama who can help me out. Bottom line is I want the best possible set up for birds, and it's either the 800 or the 600 with a 1.4 tele it seems.

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    The 500 and 600mm Canon lenses, particularly when combined with a 1D X and both TC-IIIs are way more flexible than an 800mm with a 7D or 70D, but there's a huge cost difference. You can AF at f/8 with the 1D X, the 5D MkIII and the series of 1D Mkxx bodies prior to the 1D X. The 1D-series also has more battery voltage than the 5D-series.

    If you want to shoot small birds, mostly perched, then the 800mm is a wonderful lens. I'd rather have the 500 or 600mm and combine them with either the 1.4x or 2.0x TC-III, so that I can hand hold in more situations and get to f/4 when I can get close enough to the birds. Which is best for you will depend on what you tend to shoot.

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