Nikon K1 extension ring oddity

Discussion in 'Nikon' started by edwin_barkdoll, May 25, 2015.

  1. I purchased a K1 ext ring a while ago and, having just gotten around to playing with it, I notice that when a lens is mounted on the camera the lens is rotated about 45 degrees too far clockwise (facing the camera). I can get around this to some extent by removing the stop screw and rotating the lens so that it is upside down, however, this is not terribly convenient. (The lens wobbles slightly when positioned correctly with the stop screw removed, hence the need to position it upside down)
    The 45 deg rotation is not noticeable unless the focal length is very short and the lens has a built-in lens hood, e.g. the 16mm f/2.8 FX fisheye.
    Any conjectures on why the unusual mount geometry?
     
  2. I use a K1 a lot for different things. I have never had it be an issue for me. The only lens I have with a built in hood is my 14mm f/2.8 and it and the K1 do not play well together. To achieve focus the subject is touching the front element.
    I wonder if the offset was so that the prongs on the old lenses didn't interfere with the metering heads on the F and F2
     
  3. With the 16mm the focal point is a bit in front of the lens, so that is not a problem, however the lens hood shows up in the corners of the image.
     
  4. I pulled out my F and a K-1 ring and the offset is so that the metering prong on the lens does not hit the head. If you had a non metering prism on the F it would not be a problem.
     
  5. Michael Bradtke is correct here. If you have a Photomic F you will see that the short K1 must be offset so the lens prongs don't hit the meter head. The K2 can be installed in any of three different positions, one of which gets the lens close to correct again, but not close enough for a petal hood.
    By the way, I hope you're not using an unmodified K1 with an AF lens. The inner barrel of the K1 presses against the contacts. The rest of the set is fine, but you really ought to mill/grind/file out the inside of the K1 to use it with AF lenses.
    I used a Dremel tool with a little milling cutter.
    00dJEQ-556914284.jpg
     
  6. Odd, I've been playing with the K1 & the D90 and I don't recall the angle issue. Had the 18-200VR which has a petal hood on it. Did some shaving for the lens AF contacts, and had to latch the aperture lever of the lens to open it up a bit.
    http://www.dpreview.com/forums/thread/3034839
    http://www.dpreview.com/forums/thread/3041926
    I recall the K tubes are pre-AI, and there may be issues with the aperture sensing tab on the bigger bodies?
     
  7. Though pre-AI both K1 and K2 clear the AI follower tab easily. The K1 has no rear extension, and the K2, though it has a little, is a small enough diameter that it misses it altogether.
     

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