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  1. #1
    rduraoc's Avatar
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    Minolta 135mm f2.8 focus problem

    I'm using this lens with a Maxxum 7, and sometimes I have a serious focus problem. The camera will focus on a point, and when I move from that, it can´t refocus on the new point. It just keeps moving the focus slightly back and forward, without real "hunting". I have to switch to manual focus, rotate the focus ring to another position, and then get AF again. It will repeat the problem 3-4 times, and then it's ok. This is recent, I have this lens for a few months, and it worked fine until now. I have a 50mm f1.7, and this hasn't happened to me so far ( I only got it a few days ago), so I believe the problem is in the lens and not in the body. Any thoughts?

    TIA,

    Rui Durão

  2. #2
    TheMissingLink's Avatar
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    afaik focussing works with measuring the contrast your sensor measures ... as long as the modern lenses/bodies work in the same way these days, sorry, but with this high-tech I'm not up to date.

    Sounds to me like the sensor isn't able to meter the contrast, at least not always exactly ...


    Horst
    everything becomes more worse. one thing becomes better: the moral becomes more worse.

  3. #3
    rduraoc's Avatar
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    Could it be the body, then? I just have these two lenses, anybody has an idea on how to determine whether it is the body or the lens? I can´t make it happen in the 50mm, but that might be because of the different focal distance. But I'm still inclined to blame the lens, not the body.

  4. #4
    jamesdak's Avatar
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    Does it happen on all 3 AF modes of your Maxxum 7 or one specific one? Also, you might try gently cleaning the electrical contacts of the lens itself. Make sure if you do though that nothing gets on the rear element. Other than the focus problem do you like the lens? I've been thinking of adding one to my kit. Jim

  5. #5
    Dave Parker's Avatar
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    I had the 135mm and had a simular problem with a newer body and a 1st generation lens, seems they had conflicting software problems, what your describing sounds like the problem I had, the software in the lens was not able to resolve the focal point as well as the AF sensor in the camera, I sent it to a repair shop and they were able to upgrade the software in the lens, and I have never had a problem since.

    As far as the quality of the lens, it has been a very good performer and I have used it at numerous weddings over the years.

    Dave

  6. #6
    rduraoc's Avatar
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    I normally use Single AF, and haven't (consciently) tested it in other modes. I'll do that tomorrow, when it's daytime. I had already remembered of cleaning the contacts, but they look quite clean, so I left them as they where. Maybe it needs a software upgrade, like Satinsnow suggested. I'll have to contact Minolta here.

    About quality, I like it a lot. Little distortion (very little), minimum flare, good optical quality, good build (although the built-in hood handling is a little fragile). It is great for street shooting, as I can get the people without being on their nose. Only real downside is the AF speed, quite slow, but it doesn´t bother me much.

  7. #7
    rduraoc's Avatar
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    Problem update

    My problem with this lens as evolved, and it has become clearer. The
    focus gets stuck somewhere around the middle of the way between the
    infinity and close-up focus. As the camera detects resistance to turning
    the focus ring, it comes back, believing it has reached the end of the
    focus amplitude. So, I now have two "focus modes": from infinity to
    about 2m, OR from 2m to 1m. I'm tempted to open the lens, and try to
    lubricate it, but although I've opened a few MF lenses (and cameras), I
    never opened a AF one, especially with all the electronics that I
    believe this one has inside. Anyone has any hints? Any site with useful
    information? Or should I just forget it and send it to Minolta?

    TIA,

    Rui Durão
    I am not afraid of grain.
    http://fotodura.pt.to

  8. #8
    rduraoc's Avatar
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    Also, I believe this is why the AF speed was so slow. I always expected it to be faster, and there must be a connection.
    I am not afraid of grain.
    http://fotodura.pt.to

  9. #9
    rduraoc's Avatar
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    Done.

    I took my chances, and carefully opened the lens. Inside, there were two oval pieces that adjusted the focus ring tension. Adjusted them, gave them a (really) slight lubrification, put everything back together, and it's solved. And the focus speed is much better now.
    I am not afraid of grain.
    http://fotodura.pt.to



 

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