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Thread: Lens' maximum aperture & AF sensitivity

  1. #1

    Default Lens' maximum aperture & AF sensitivity

    Dear expert,

    Who could explain what is lens' maximum aperture & AF sensitivity??? How it helps in photo shooting?

  2. #2
    Member Irvine's Avatar
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    Default Re: Lens' maximum aperture & AF sensitivity

    Quote Originally Posted by TBing View Post
    Dear expert,

    Who could explain what is lens' maximum aperture & AF sensitivity??? How it helps in photo shooting?
    when the lens is mounted on the camera, it will be switched to maximum aperture to maintain a viewfinder as bright as possible. this also helps the AF points to detect contrast n focus more accurately. so from this theory alone, bigger aperture = more light enters thru the lens, n u will get a brighter viewfinder + the AF points receive more light for focusing. since there's more light available, it will be easier for the AF points to detect the contrast n focus accurately. this is particularly useful when tryin to focus in low light situations.

    otherwise, smaller max aperture = less light enters the lens = dimmer viewfinder and the AF system will hunt more than usual in dark situations.

    hope this helps
    Google is your friend. Make use of it.

  3. #3

    Default Re: Lens' maximum aperture & AF sensitivity

    I read from manual saying that "max aperture up to 5.6 the cross-type AF sensitive to both vertical & horizontal lines are possible". What does this mean???

    "With 2.8f, the center AF point's sensitivity to vertical & horizontal lines is about twice as sensitive as the other AF points". What does this mean as well?

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    Member Irvine's Avatar
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    Default Re: Lens' maximum aperture & AF sensitivity

    Quote Originally Posted by TBing View Post
    I read from manual saying that "max aperture up to 5.6 the cross-type AF sensitive to both vertical & horizontal lines are possible". What does this mean???

    "With 2.8f, the center AF point's sensitivity to vertical & horizontal lines is about twice as sensitive as the other AF points". What does this mean as well?
    this will help u understand better:
    http://www.cambridgeincolour.com/tut...-autofocus.htm
    Google is your friend. Make use of it.

  5. #5

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    I just bought my 50mm camera. Sometimes when I get too close to the subject, i am not able to press the shutter. Why is that so? Is there a min distance to shoot from? Thanks!

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    Moderator daredevil123's Avatar
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    Default Re: Lens' maximum aperture & AF sensitivity

    Quote Originally Posted by icy55 View Post
    I just bought my 50mm camera. Sometimes when I get too close to the subject, i am not able to press the shutter. Why is that so? Is there a min distance to shoot from? Thanks!
    Read up on MFD - Minimum focusing distance.

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