Focus speed

Discussion in 'Sports' started by neil_everitt, Oct 20, 2008.

  1. Is there anywhere a comparison of the auto focusing speeds of the various Canon L lenses? Some are quite obviously faster than others.

    I currently benchmark everything against the 300 2.8L, which I think is fabulously fast to focus, but I also require something shorter. I
    use a 70-200 2.8L, the Mkl version, but its focusing speed and accuracy invariably leaves me disappointed. Is the Mkll IS version faster or
    would I be better going for a prime 200mm 2.8L?
     
  2. canon 135mm f2
     
  3. Hi Neil,

    I have the 300 and the 70-200 f2.8 IS, I don't notice a difference in focus speed between them, they both seem instantaneous to me, the 300 does slightly better in lower light but can be made to hunt more if AF point selection isn't used well, they are both very very good.

    I found the 135 f2 to be slower, noticeably, than the zoom. The 85 1.2 and the joke of AF on the 50 f1 are the true L lens slugs though. I have never used the EF 200 f2.8 but was lucky to use the 200 f1.8 and that AF's like the 300 even with the very narow dof.

    Take care, Scott.
     
  4. I use 500mmf 4 IS, 300mm f2.8 IS and 70-200mm f2.8 non IS. The focus speed difference between these is very very small. This is using 1dmk2 body.

    I am not sure why you having focussing problems with your lens.
     
  5. Focusing speeds on lenses have improved over the years, and we're only talking differences of milliseconds, but those
    differences can be make or break in sport.

    Scott: My 70-200 is the Mkl, non IS, which may be slower than your Mkll IS.

    Strangely, shutter lags on camera bodies are quoted but lens focusing speeds never are. Why?
     
  6. Hi Neil,

    What bodies are you using, it makes a huge difference. I suppose that is why lens focus speeds are not listed, as the AF improves it gets better, unrelated to the lens, and all the different camera models would need speeds worked out. Interesting though, can you imagine the arguments about test parameters, simulating moving real world type subjects, contrast and AF point issues, wow it would give some people more to talk about than pixels though!

    Any chance you could rent an IS model for a weekend to see how it compares to yours? I played with the two lenses you mentioned after posting and my reply was correct.

    Take care, Scott.
     
  7. Hi Scott,

    I'm mainly using 1DMkll and lll, and I would assume that, as you say, speeds are relative to bodies used. In other words, if the
    body's AF focusing ability improves so does that of the lens used on it, but a 'slower focusing' lens is still never going to
    match a 'faster focusing' lens on the same body.

    As all figures would be relative, I can see nothing to stop Canon (or any other manufacturer) using a standard set of
    conditions to test lens focusing speeds. And they wouldn't have to do it on all bodies. For instance, if Canon were to
    create a standard set of conditions and test lenses on any camera, a 5D, say, they might come up with a set of figures
    in milliseconds. The actual figures wouldn't be important but you would be able to see which lenses were faster than
    others and, presumably, these differences would be duplicated (to a greater or lesser extent) across the entire range of
    Canon bodies, whether you were using a 20D or a Mklll.
     

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