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Navitar 25mm F0.95 c-mount

Discussion in 'Adapted Lenses' started by RobWatson, Jul 6, 2011.

  1. RobWatson

    RobWatson Mu-43 Hall of Famer

    Playing around with the E-P1 and an old c-mount lens I've had for ages. The vignettng is modestly pronounced and shows how far off center the lens mount is with respect to the sensor (I wonder if everyone elses E-P1 sensor is offset so much).

    There is a weird effect on the tree shots that reminds me of the diorama filter. Also the bokeh is odd due to lots of spherical abberation. The lens sharpens up pretty good when stopped to F2.8.

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    This flower in front of the office is a frequent test subject. Here at F0.95.

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    Same flower but stopped to F2.8

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    Another frequent test subject is the tree in front of the office. @F0.95

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    And at F2.8

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    • Like Like x 1
  2. retnull

    retnull Mu-43 Regular

    Feb 12, 2010
    It's a cool look. This might be a great lens to use in square aspect ratio.
  3. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Just pretend you're using a full frame camera. ;)  Just kidding.
  4. RobWatson

    RobWatson Mu-43 Hall of Famer

    Yeah, I wanted to leave the vignetting in case anyone else really wanted to use the lens just so there would be no surprises. Technically the lens is a 1" format so only a 16mm image circle but there is quite a bit more than that but the abberations get pronounced out there.

    The other nifty thing about this lens is it is fairly small. Maybe 1/4 the size of the Nokton 25mm F0.95 (not to suggest any direct comparisons).
  5. apicius9

    apicius9 Mu-43 Veteran

    Feb 1, 2010
    Philadelphia, PA
    That's still strange, I have never before seen the vignetting so much off center before - is that really normal for the EP1?

  6. thearne3

    thearne3 Mu-43 Top Veteran

    Jan 28, 2010
    Redding, CT USA
    Do you have any other c-mount lenses to compare for the off-center effect? If the sensor is truly off center, then even regular lenses would be affected. I hope for you sake that it is the mount/lens in this case!

    BTW, most pics using a 25mm c-mount that I've seen have far less vignetting. The Cosmicars and Computars, for example.

    A fast lens adapted lens is always fun...I don't mean to throw cold water on the experience! :biggrin:
  7. sLorenzi

    sLorenzi Mu-43 Top Veteran

    Sep 15, 2010
    Couldn't it be an adapter problem? To me the photos look a little "tilted" the way it looks when using a lensbaby, or is it just my eyes?
    BTW I have a G1 and my "No brand" c-mount 25mm has strong vignetting when stopped down, but it's centered.
  8. RobWatson

    RobWatson Mu-43 Hall of Famer

    Sensor off ccenter

    Just by visually inspecting the camera it is clear that the sensor is well off center. An asymmetric vignetting pattern is clearly seen (if looked for) on all the lenses I've used - native and adapted.

    If I had another camera handy I'd post a photo... it does not particularly bother me.

    F0.95 and 25mm focal length are pretty extreme so a significant amount of vignetting is to be expected. Given the 1" format there is likely even some stopping on top of the vignetting.
  9. RobWatson

    RobWatson Mu-43 Hall of Famer

    Oops ...

    I slipped on some rocks at the sea shore ...

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    The Navitar 25mm F0.95 'jumped' out of my cambag and into the drink!

    After extracating myself from the sharp barnacles ...

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    I fished out the lens but the water moves fast and drew in a fair amount of fine silt as well. Got home and forgot about the lens until the next day. The salt water had done its work and things got hard to move. I took the lens apart and got it all cleaned up (that silt gets everywhere). Except for the dinged filter threads eveything is back in fine working order.

    Next time I'll have to remember to actually close the cambag all the way.
  10. RobWatson

    RobWatson Mu-43 Hall of Famer

    Just to bring some closure to this topic ...

    The problem is my IBIS is actually not functioning and the sensor is 'parked' off-center and tilted a bit.
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