70-200mm Autofocus

Discussion in 'Beyond the Basics' started by Tighearnach, Jul 24, 2008.

  1. Tighearnach

    Tighearnach TPF Noob!

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    Hello

    I was wondering if anyone knew whether there was a significant difference in autofocus speeds in the Canon 70-200 f/2.8 and Canon f/4.

    Also i was thinking of buying Sigma 70-200mm f/2.8 instead of Canon f/4. How do the autofocus speeds of these two compare?

    Thanks for any help
    T
     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    The two (or four) Canon lenses have USM ring focus motors...so they are very fast. I don't know which is faster but I wouldn't be surprised if the F4 is a little faster because it's a bit smaller. But the F2.8 is still pretty fast.

    I don't know about the Sigma, I think their fast AF lenses are HSM.

    There is also a new 70-200 F2.8 lens from Tamron to consider.

    Keep in mind that the camera body is also a factor is the speed of the AF.
     
  3. Tighearnach

    Tighearnach TPF Noob!

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    to follow up on this.

    If your shooting sport etc and you can choose between the sigmaf/2.8 and canonf/4. If the canon autofocus is significantly faster than the sigma2.8 is there a point to getting the sigma over the canon. The sigma might be faster but if you cant focus instantly then that narrower depth of field and higher shutter speed is irrelevant no? Photos will be soft yeah...
    Talking about photographing fast objects here like sports, birds in flight etc....
    P.S Sigma could be lightning quick in autofocus. I dont know.
     
  4. icassell

    icassell TPF Noob!

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    My Sigma 50-150mm f2.8 HSM is extremely fast AF
     
  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    If you can't get the shot because the lens is too slow...that's no good. If you can't get a fast enough shutter speed because the aperture is limited to F4, that's no good either. But at least you could turn up the ISO to gain some shutter speed (but get more noise).

    I don't know if the Sigma 70-200mm has HSM, if so, then it would probably be a good option. If not, then the Canon would probably be getter.

    Also, there is more to getting accurate focus than just the speed of the lens & camera. After all, people have been shooting sports and moving objects since long before auto focus was invented.

    Or you could just do what I did...and buy the best 70-200 lens avaliable for your camera. The Canon 70-200 F2.8L IS. Then you never have to worry that you didn't buy the right/best lens.
     
  6. Tighearnach

    Tighearnach TPF Noob!

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    Thanks for the help.
    As for the 2.8 with IS. Id love it but think i would use the f/4 more, simply because of its size and weight in comparison. I like walking around with lenses (even tho my question related specifically to sport/nature i need this lense for multiple uses) and although i havent ever held one ive seen a lot of comments on this site as to the weight of it.

    It seems tho that if the Sigma has HSM it is very fast.
    And i take your point MIke on the photographer being essential to focused sharp photography but that is why i need every bit of help i can get!
     
  7. RyanLilly

    RyanLilly No longer a newbie, moving up!

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    The sigma does have HSM and is very fast, and is supposed to be a fantastic lens, I have the non-IS canon f4 and it is pretty small and light, and I do like the lens, but I'd personally trade those features for an extra stop if I could.
     

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