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Thread: Lens appears to front focus, but actually isn't?

  1. #1
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    Default Lens appears to front focus, but actually isn't?

    Anyone ever experience such a weird situation with large aperture prime whereby the lens appears to have front focus on focus chart and "battery test" but yet is focusing correctly in real world usage?

  2. #2
    Moderator daredevil123's Avatar
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    Default Re: Lens appears to front focus, but actually isn't?

    happens all the time.

    It is called focus shift.

  3. #3

    Default Re: Lens appears to front focus, but actually isn't?

    I encountered it with a prime lens 50mm f1.7 which I have recently purchased. I thought either my lens or camera went bonkers..
    I even plan to send my camera in for service.

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    Senior Member luckyorange's Avatar
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    Default Re: Lens appears to front focus, but actually isn't?

    Quote Originally Posted by xtunbox View Post
    I encountered it with a prime lens 50mm f1.7 which I have recently purchased. I thought either my lens or camera went bonkers..
    I even plan to send my camera in for service.
    50mm f1.8 i guess?
    Lousy de My Flickr

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    Default Re: Lens appears to front focus, but actually isn't?

    Quote Originally Posted by luckyorange View Post
    50mm f1.8 i guess?
    I think there IS a 50mm f/1.7

    http://www.kenrockwell.com/pentax/35...-f17-smc-m.htm
    Too many great equipments but too little quality photos. [My Flickr] | [My Blog]

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    Member Irvine's Avatar
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    Default Re: Lens appears to front focus, but actually isn't?

    Quote Originally Posted by luckyorange View Post
    50mm f1.8 i guess?
    he's a pentax user n there is such a lens for pentax
    Google is your friend. Make use of it.

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    Senior Member luckyorange's Avatar
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    Default Re: Lens appears to front focus, but actually isn't?

    Quote Originally Posted by SkyStrike View Post
    ow thanks for the information.. hahah opps sorry =)
    Lousy de My Flickr

  8. #8

    Default Re: Lens appears to front focus, but actually isn't?

    Can be a couple of things :
    1. Check your viewfinder diopter. You can adjust that.
    2. Focus screen is not properly calibrated wrt AF sensor. (so sensor is accurate but screen is not); Can try service center or focus screen need adjustments via shimming.
    3. AF inaccuracy
    4. Something else, go to service center.

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