SLR cameras .... fast auto focus.....

Discussion in 'Digital Photography' started by advid, Oct 27, 2003.

  1. advid

    advid Guest

    ...... lots of moans on here about the speed of focusing and 'lock on'
    of many reviewed digital SLR's.... question :-
    Isn't this focussing speed to do with the lens used (ie. isn't the
    focusing motor/mechanism built into the attached lens and it's this
    that does the focusing 'work' ?)
    Any help in explaining this further would be most welcome....
    advid, Oct 27, 2003
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  2. advid

    George Guest

    The motor speed, built into the lens or the body, is only part of the
    equation. The rest has to do with the sensors (in the body) and the
    algorithm that decides that everything is in focus and what to do if it
    isn't in focus. Some older bodies spend a lot of time "hunting" (focusing
    back and forth) to find the proper focus.
    George, Oct 27, 2003
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  3. In modern dSLRs, the lens is the limiting factor. Nikon's AF-S lenses, with
    the "Silent Wave" focusing motor are VERY fast and accurate. As well as

    Howard McCollister, Oct 27, 2003
  4. advid

    Lionel Guest

    Point and Shoot
    What the hell is wrong with you?
    Lionel, Oct 27, 2003
  5. advid

    advid Guest

    .. .... does this mean that less costly lenses (Sigma etc etc) are slower to
    focus because of a 'lesser' motor/mechanism and therefor would 'hunt'
    slightly more before focussing ?

    I'm referring back to the time when lots of moans and groans about the Canon
    D30 dSLR being not as good as its SLR/Film 'brethren at the time because of
    its slow(ish) focus and sometimes not good at locking on in low light etc.
    Surely this would depend a lot on the quality/ make/ model of the lens that
    was being used on the camera....

    Would a D30 be 'loads better' with a £1000 top line Canon lens compared to a
    £150 Sigma ? (I'm not talking about picture quality /sharpness - just focus
    speed and lock on accuracy)
    advid, Oct 28, 2003
  6. advid

    Jim Davis Guest

    I have a 10D. Today, I saw a heron flying by me and quickly put the
    camera to my eye and snatched off three quick shots. Fortunately, the
    camera was in my usualy servo focus. All three were in sharp focus.
    All three were taken within the 2 seconds I had before the bird flew

    In other words, I didn't wait for focus, I just pointed and shot.
    Bingo. EF100-400L IS mode 1. Yes, mode 1 is just fine for panning.
    Jim Davis, Oct 29, 2003

  7. Yes. It depends on the lens. If it has a built in motor, it will focus much,
    much faster than if it has to rely on the camera's motor a la Nikon. I tried
    out a big, long lens the other day without a motor, and it took so long for
    the onboard motor to focus I could have done it three times manually.

    Brian Zinchuk, Nov 6, 2003
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