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Sigma 20-40 DOF preview issue

  • 08-10-2010 10:03PM
    #1
    Ricky91t
    Closed Accounts Posts: 6,281 ✭✭✭


    OK,

    This is a weird issue, This just happened one day while I was shooting multiple frames, I never use the DOF preview button and probably hadn't used it for months prior to this, But while I was shooting the image started getting darked as if the button was pressed, The camera was still reading F/4 but the images looked to be shot at f/20, First it went straight to a very low aperture f/8 then f/16 and then f/20.

    It has continued to do this and makes the lens unusable, I've also got a 100-300 f/4 and 70-200 f/2.8( both sigma ) but it is just specific to my 20-40 f/2.8...

    Has anyone ever has this issue? How have you resolved it?

    Thanks


Comments

  • #2
    zerohamster
    Registered Users, Registered Users 2 Posts: 1,792 ✭✭✭zerohamster


    I cant say for sure if its a faulty diaphragm but try cleaning the contacts on the lens and camera with a rubber eraser, might do the trick.
    does the lens stay at f/20 constantly or just when you are composing? can you change the aperture at all?


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