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  1. #1

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    Pentax S3 lens stop down problem

    I just got this very clean Pentax S3 and it has a problem. When I put the lens on A the aperture is supposed to stop down to the set aperture before exposure but I found that sometimes it only stops down partly or not at all. The problem is worse if the camera is pointed upward (lens pointing up). The problem is not so much if the lens is pointed downward. At long exposure like 1 sec I could see that the aperture would stop down slowly to the set aperture. The aperture stop down pin on the lens actin feel normal. It doesn't feel tight so I don't think it's the lens. When pointing the camera upward sometimes it gets so bad that the camera could not complete the cycle.
    I would greatly appreciate and help on this matter.

  2. #2

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    Sticky lens diaphragm.

  3. #3
    benjiboy's Avatar
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    Needs a C.L.A.
    Ben

  4. #4

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    Chan, I think pushing the pin on the lens doesn't close the diaphragm, it releases the diaphragm so it can be closed by an internal spring. This is why it doesn't feel tight. Even if it doesn't work the way I think, it would take very little drag to slow things down. When the lens is pointing up, the blades are probably lying on each other and dragging.

    Check it with a different lens on that body to be certain it is the lens.

  5. #5

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    Quote Originally Posted by E. von Hoegh View Post
    Chan, I think pushing the pin on the lens doesn't close the diaphragm, it releases the diaphragm so it can be closed by an internal spring. This is why it doesn't feel tight. Even if it doesn't work the way I think, it would take very little drag to slow things down. When the lens is pointing up, the blades are probably lying on each other and dragging.

    Check it with a different lens on that body to be certain it is the lens.
    This is the screw mount lens exactly it's the Auto Takuma 55mm f/1.8. Pushing the pin IN close the aperture when the stop down switch on the lens is set at A. When it's set at M the lens is always stopped down to the set aperture. Not like the new Pentax K mount that letting go of the level close the aperture.

  6. #6
    Jerevan's Avatar
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    Send it off to Eric at www.pentaxs.com - he does a good job. It could be a combination of the lens and the body needing CLA, as it was in my case (Pentax S1a).
    “Do your work, then step back. The only path to serenity.” - Lao Tzu

  7. #7
    Bill Burk's Avatar
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    Just take the lens off the camera and push the pin in. You'll see soon enough if the lens is the issue.

    p.s. I had the Spotmatic F w/50mm f/1.4 around my neck while reading this so all I had to do was take off the lens and try it myself...

  8. #8

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    Quote Originally Posted by Bill Burk View Post
    Just take the lens off the camera and push the pin in. You'll see soon enough if the lens is the issue.

    p.s. I had the Spotmatic F w/50mm f/1.4 around my neck while reading this so all I had to do was take off the lens and try it myself...
    Like I said in the first post, taking the lens out and pushing the pin it works with little resistance. It seems that the camera spring doesn't supply enough force to push the pin.

  9. #9

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    Yes but does the lens stop down when you push the pin? Or does it stick?

    And if it does stop down, then have you checked the function of the diaphragm plunger in the camera? Is it slow or sticking?
    Last edited by Yashinoff; 09-20-2012 at 12:45 PM. Click to view previous post history.

  10. #10

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    The lens stop down with very light pressure on the pin when I had it out of the camera. The diaphram doesn't look oily. However, when the lens is out the pusher plate move quickly and doesn't seem to have a problem.

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