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Thread: Need help on focusing

  1. #1
    Member gymak90's Avatar
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    Default Need help on focusing

    The other day I was using canon 50mm F1.8 and also canon 75-300mm F4-5.6.

    I realised most(if not all) of the photos I took are not correctly focused. I used AI Servo and my subjects were fast moving. I had soccer players, runners etc.

    Both lens do not have USM, so probably the focusing is slower, but will that cause the pics to be out of focus? Afterall the camera gave me the 'beep' and I believed it was focused.

    Or is it my shooting technique? I usually aim at my subject and half-press and wait and hold, until the moment comes, then I do a full-press. Is there anything wrong?

    Hope to get some clarification. Thanks

  2. #2

    Default Re: Need help on focusing

    Quote Originally Posted by gymak90 View Post
    The other day I was using canon 50mm F1.8 and also canon 75-300mm F4-5.6.

    I realised most(if not all) of the photos I took are not correctly focused. I used AI Servo and my subjects were fast moving. I had soccer players, runners etc.

    Both lens do not have USM, so probably the focusing is slower, but will that cause the pics to be out of focus? Afterall the camera gave me the 'beep' and I believed it was focused.

    Or is it my shooting technique? I usually aim at my subject and half-press and wait and hold, until the moment comes, then I do a full-press. Is there anything wrong?

    Hope to get some clarification. Thanks
    If you lock focus and hold it there, the players might have already moved when you release the shutter. In a situation like this, it might be better to use continuous servo focus mode and see if there is a function on the camera to track the focus.

  3. #3
    Moderator Octarine's Avatar
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    Default Re: Need help on focusing

    Quote Originally Posted by gymak90 View Post
    The other day I was using canon 50mm F1.8 and also canon 75-300mm F4-5.6.

    I realised most(if not all) of the photos I took are not correctly focused. I used AI Servo and my subjects were fast moving. I had soccer players, runners etc.

    Both lens do not have USM, so probably the focusing is slower, but will that cause the pics to be out of focus? Afterall the camera gave me the 'beep' and I believed it was focused.

    Or is it my shooting technique? I usually aim at my subject and half-press and wait and hold, until the moment comes, then I do a full-press. Is there anything wrong?

    Hope to get some clarification. Thanks
    AFAIK, AI Servo will not give you any acoustic feedback, just the focus point that caught the object will flash red. Have you checked which of the focus point was red? Was it the one directly aiming at the object?
    When you get this 'beep' you were not in AI Servo but in AI Focus. That could explain why the focus wasn't adjusted to the moving object: if the camera doesn't detect any change the focus won't be adjusted - no switch to AI servo as it is supposed to be when a moving object is recognized.
    The 50mm has such a thin depth of field that at f/1.8 it is easy to miss the correct focus, especially with fast moving objects. Use smaller aperture (>5.6) if the light condition permit.
    For sport and action you might want to use Tv mode, AI servo and continuous shooting.

  4. #4
    Member gymak90's Avatar
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    Default Re: Need help on focusing

    AI Servo is supposedly Canon's lingo for continuous focusing with focus tracking is it?
    Sorry I'm not that familiar here.

    I'm quite sure the focus point that turned red was the one i selected. Yea I agree the player might moved off.
    There were instances when the player stood still, waiting for the ball to roll to him. I fired off when he attempted to kick the ball back. So actually his upper body didn't move, only his lower body did.
    It turns out even his face wasn't properly focused.
    Sorry I think I deleted the photo, will go check again

    Will a lens without USM serious impair the ability to focus correctly and capture fast moving objects? I failed to take pictures of sprinters, haha.

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