Problem with Nikon 50mm 1.8 AF

Discussion in 'Nikon' started by Steve, Feb 23, 2008.

  1. Steve

    Steve Guest

    I recently purchased two used lenses from different sources, and just
    received them in the mail (yea!). Both are nikon: 85mm and 50mm 1.8
    lenses. However, when comparing images from the two, I'm noticing that
    the 50 is consistenly 1 exp position underexposed. I can compensate in
    the auto modes by bumping up the exposure, so I first thought this
    might just be a meteringt thing. However, I just tried a comparison
    shooting outdoor shots in full manual. For the same shutter speed
    (1/60), f/8 ap on the 85 gave the same as f/5 for the 50mm. f/8 on the
    50 was a LOT darker...

    Is this normal, and if not, what can I do (short of getting rid of the
    lens) .

    Thanks.
    -Steve
     
    Steve, Feb 23, 2008
    #1
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  2. Steve

    Paul Furman Guest

    Not normal & I never heard of such a thing. If the aperture blades were
    sticking it'd be overexposed but still you might look through the
    dismounted lens while flipping the tab on the back & turning the
    aperture ring. Maybe if it's stuck & never opening fully it would do that.
     
    Paul Furman, Feb 23, 2008
    #2
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  3. Might it be possible that the aperture blades are sticking -
    but on the 85mm: the 50mm is working OK but the '85 is
    overexposing 1 stop?

    Very strange, though.

    Questions:

    1) If the lenses are demounted and you look through the lens as
    you turn the aperture ring do they both stop down about the
    same amount for each click of the ring?

    2) If you set the rings for f8 and then slowly open and close
    the aperture with the aperture pin do they close down to
    same point all the time, what if the pin is flicked?

    3) What camera are you using and what mode is it on?
     
    Nicholas O. Lindan, Feb 23, 2008
    #3
  4. Steve

    Paul Furman Guest

    4) Does it underexpose wide open or only at certain apertures?

    Vignetting will make the corners somewhat darker when wide open but the
    center should be OK.
     
    Paul Furman, Feb 23, 2008
    #4
  5. Steve

    Steve Guest

    Shooting a D50 in fulkl manual mode, outdoor (although same prob
    occurs when using flash). The 85 actually seems to overexpose just a
    tad relative to the kit lens, and I've had to use it at around -.3 or
    -.7 to produce the best results. I tried setting shutter speed to
    1sec, then look actuallyt watch the aperture close for all settings
    between 1.8 and the max for each lens, and it doesn't look like
    anything is sticking. I was wondering if something might actually be
    miscalibrated?
    Thanks.
    -Steve
     
    Steve, Feb 23, 2008
    #5
  6. Steve

    Steve Guest

    Oh, and so far, this underexposure appears to hold for all apertures.
    I think I will try to borrow a friend's 50mm, and see if the same
    thing occurs...
    -Steve
     
    Steve, Feb 23, 2008
    #6
  7. Try putting the camera on manual mode, opening the lens all the way, and,
    using a light meter, adjust the lighting until the exposure should be right
    on the money.....Then see how the pictures come out.

    And, even before those pictures are developed, put another lens on the
    camera and do the same thing. Are the adjustments different for the same
    lighting level? If they are, then look for a filter on the front of the
    lens. If no filter, then the lens must be defective.....Someone must have
    messed with the elements, or put a coating on one of them......Or, the
    aperture adjustments must have been messed up upon reassembly......Does the
    aperture scale go all the way at both ends? i.e.: can you close it down all
    the way, as well as open it up all the way?
     
    William Graham, Feb 23, 2008
    #7
  8. There is another possibility.....The mount on Nikkors has a cutout on it
    that tells the camera what the speed of the lens is......I forget just where
    it is, but they mill a depression somewhere that tells the camera
    this.....It could be that the lens has the wrong mount on it, or the
    depression is filled up with crud, or something is wrong here, so the camera
    thinks your lens if faster than it really is......
     
    William Graham, Feb 23, 2008
    #8
  9. Steve

    bob Guest

    Steve try taking a reading of a white sheet o f paper which has even
    illumination . Do not use matrix metering .

    The Photographs you are taking the 50mm will include more "sky" and cause
    the metering to under expose.
    Are you using digital or Film. With Film te printers tend to compensate :(
     
    bob, Mar 7, 2008
    #9
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