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Thread: Blurry when near, sharp when far, what happened?

  1. #1

    Default Blurry when near, sharp when far, what happened?

    Hi all,

    I am using a 300D with Sigma 18-125 f3.5-5.6 DC, btw the lens says its minimum focusing distance is 50 cm.

    I found that focusing on distant subject I get sharp and clear picture. However, focusing closer objects (within 2 m or so), at 100% magnification the image is blurry. Suspected motion blur but tripod and flash doesn't help. Raising F number to 8 or 16 doesn't help too. Ironically I find my old camera Sony DSC-F717 is sharper, be it near or far.

    What's wrong? Camera focussing problem? Or lousy lens?

    Thanks.

  2. #2
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    You sure you haven't exceeded the minimum focusing distance of the lens?

  3. #3

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    when near u can't zoom in too much...the lens couldn't focus

    its like standing or placing the camera too close to the lens

    try to put a finger at ur eye...cannot see also

  4. #4

    Default

    Positive, When I shoot people I don't shoot in front of their nose .

    ALso did some experiment taking picture of text in book, which I think best demostrate sharpness.

  5. #5

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    Quote Originally Posted by icelemontea
    when near u can't zoom in too much...the lens couldn't focus

    its like standing or placing the camera too close to the lens

    try to put a finger at ur eye...cannot see also
    Yup, I understand that most compact camera's minimum focusing distance will be increased when zoomed in. But this lens can focus anything within 50 cm no matter what zoom state is it in.

    And I don't think taking portrait shot 2 m away from subject is too near.

  6. #6

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    I own this lens. I realise when I set to full zoom @125mm and focus near, the focusing is not accurate. You have to use manual focus.
    See my Photo Gallery at the Clubsnap

  7. #7

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    Quote Originally Posted by megaweb
    I own this lens. I realise when I set to full zoom @125mm and focus near, the focusing is not accurate. You have to use manual focus.
    I see, that might explains it, what do you think of the focusing accuracy in wide angle?

  8. #8
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    Quote Originally Posted by Daniel Nielson
    Yup, I understand that most compact camera's minimum focusing distance will be increased when zoomed in. But this lens can focus anything within 50 cm no matter what zoom state is it in.

    And I don't think taking portrait shot 2 m away from subject is too near.
    My apologies. I realized i didn't read your initial statement that the lens has a min focusing distance of 50cm.

    So i guess we've got some feedback from another user. Either get around it somehow, or dump it.

  9. #9

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    Quote Originally Posted by Reflection
    My apologies. I realized i didn't read your initial statement that the lens has a min focusing distance of 50cm.

    So i guess we've got some feedback from another user. Either get around it somehow, or dump it.
    No problem.

    I just bought it, it will be my nightmare to dump it so soon.

  10. #10

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    Quote Originally Posted by Daniel Nielson
    I see, that might explains it, what do you think of the focusing accuracy in wide angle?
    So far no problem. See some of my wide angle closeup shots taken as follows:

    http://megaweb.clubsnap.org/20d/ho_c...h/img_7250.htm

    http://megaweb.clubsnap.org/20d/ho_c...h/img_7559.htm

    http://megaweb.clubsnap.org/20d/ho_c...h/img_7529.htm
    See my Photo Gallery at the Clubsnap

  11. #11

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    Quote Originally Posted by megaweb
    I see.

    Thanks, not the best lens, but I guess not too bad either.

  12. #12

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    Just an update btw, I am not sure why but I don't have this problem anymore, the focusing is ok now, near or far, wide or telephoto. May be because I have changed the focusing screen?

  13. #13
    Senior Member
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    Now I know why so many people are selling this lens on CS.

  14. #14

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    After 4 days of intensive use during a trip in the past few days, I would say it produces decent pictures now, well of course not to compare it with the Canon L series lenses, for the price and the zoom range, I'd say I preety like it and it is not bad for a walk around lens.

  15. #15

    Default

    Quote Originally Posted by Daniel Nielson
    Hi all,

    I am using a 300D with Sigma 18-125 f3.5-5.6 DC, btw the lens says its minimum focusing distance is 50 cm.

    I found that focusing on distant subject I get sharp and clear picture. However, focusing closer objects (within 2 m or so), at 100% magnification the image is blurry. Suspected motion blur but tripod and flash doesn't help. Raising F number to 8 or 16 doesn't help too. Ironically I find my old camera Sony DSC-F717 is sharper, be it near or far.

    What's wrong? Camera focussing problem? Or lousy lens?

    Thanks.
    Minimum focusing distance is measured from your sensor (I think AF sensor?) to your subject, not ur lens' front element.

  16. #16

    Default

    Focusing Distance is from the film/sensor to the object

    Working Distance is from the front lens to the object
    See my Photo Gallery at the Clubsnap

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