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Thread: Focusing "run" after a period of time?

  1. #1

    Default Focusing "run" after a period of time?

    Hey guys..just wondering if this ever happen to anyone of you..not sure if it's applicable to all manufacturers or anything...

    I'm holding a 50D and Sigma 17-50mm lens..when I 1st bought the lens it was sharp out of the box at all aperture and focal lengths..been using and not abusing it for a year now..whilst PPing my latest batch of photos I realised that it was back focusing quite abit..so I took out my camera and made some microadjustments and realised I had to bring the value to -10 to get a sharp subject..haven't got the chance to print out a focus chart to adjust so will do it tonight..

    My shooting style hasn't changed all these time..recently I did send my camera body to change shutter button and clean pentaprism but i do not think that it will affect the focusing of the lens..using the al cheapo 50mm it is still sharp at f1.8 with no focusing issues..just wondering if it's a lens thing or specific brand thing or just something that normally happens?

  2. #2
    Senior Member giantcanopy's Avatar
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    Default Re: Focusing "run" after a period of time?

    Front/back focusing issues are not uncommon. my 50mm and 24mm prime lenses require some microadjustment as well.
    Legitimate minor variations in camera/lens manufacturing within production tolerances, I will not be too concerned about it.
    Of course if it is really off the mark, you might want the service center to tweak and review.

    Ryan

  3. #3

    Default Re: Focusing "run" after a period of time?

    Quote Originally Posted by giantcanopy View Post
    Front/back focusing issues are not uncommon. my 50mm and 24mm prime lenses require some microadjustment as well.
    Legitimate minor variations in camera/lens manufacturing within production tolerances, I will not be too concerned about it.
    Of course if it is really off the mark, you might want the service center to tweak and review.

    Ryan
    I do understand that mass manufactured products will have some variations..I'm just wondering if it's possible that for 1 single copy of lens that was focusing well out of the box..can have it's focusing off and in need of adjustments after some time of usage?

  4. #4

    Default Re: Focusing "run" after a period of time?

    I wouldn't be surprise when after a period of use, the mechanism goes slightly off

    For Anything with electronics and moving parts, there is always a chance of that happening

  5. #5
    Moderator Octarine's Avatar
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    Default Re: Focusing "run" after a period of time?

    Have a read here: LensRentals.com - The Limits of Variation
    LensRentals.com - Notes on Lens and Camera Variation
    Variation not only occurs between different copies of the same lens, but also occurs between consecutive shots with exactly the same camera and lens. The AF is never absolute precise, variations can occur even if you have a stationary setup and just press the shutter button again.
    EOS

  6. #6
    Moderator Octarine's Avatar
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    Default Re: Focusing "run" after a period of time?

    Have a read here: LensRentals.com - The Limits of Variation
    LensRentals.com - Notes on Lens and Camera Variation
    Variation not only occurs between different copies of the same lens, but also occurs between consecutive shots with exactly the same camera and lens. The AF is never absolute precise, variations can occur even if you have a stationary setup and just press the shutter button again.
    EOS

  7. #7

    Default Re: Focusing "run" after a period of time?

    Quote Originally Posted by Octarine View Post
    Have a read here: LensRentals.com - The Limits of Variation
    LensRentals.com - Notes on Lens and Camera Variation
    Variation not only occurs between different copies of the same lens, but also occurs between consecutive shots with exactly the same camera and lens. The AF is never absolute precise, variations can occur even if you have a stationary setup and just press the shutter button again.
    Thanks for the links Octarine! Quite informative..oh well..i guess I just hafta live with the micro adjustments for now..it's no good if I'm shooting at f2.8 and the focus is behind the subject instead of the face

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