Nikon 50mm 1.2 Ai Range finder coupled Nikkor F

E

Erik Gunst Lund

Kind regards Erik
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I found a perfect match for the 50mm Ai 1.2 the Leica M8 with it's 1.33 crop really copes well together, and since the range finder is set for neutral for their 50mm lenses (51.4mm actually) it means that you can couple a Nikon 50mm directly with the range finder.
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I got a donor Leica lens 13.5cm Hektor where I could use the 39mm LTM mount to fit over the rear of the lens cell and the range finder arm connected to it through the Nikon F mount further through a Novoflex adapter.
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Calibration was tedious as always, but the Tuborg test image turned out sharp in the end.

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The lens has an pleasing soft look wide open that masks the slim dof very well, very nice for night/evening/morning captures and indoor low light shooting.

Already at f/2 its very sharp across the whole frame of the M8, I have coded it as an Noctilux f/1.0 and the camera picks that up very nicely reporting f/1.2 when shot wide open.

In all documents I have seen it is stated that the optics are identical to the 50mm 1.2 Ais except for the number of aperture blades, this is not the case, the rear element of the Ai is larger than the Ais, but the vignetting is worse for the Ai than the Ais version, some optical tuning has clearly been done, this has no consequence for use on the 1.33 crop M8, so the Ai version with it's much longer focus throw, about 180 deg is very good for this conversion, very easy to focus.
(Also posted on Leica Camera Forum)
 
I was able to restore the blur circles completely.

I relocated the two screws and shortened the range finder arm in the lens, it's now about 2 mm from the rear element and with a concave chamfering the blur circles clears
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Very happy about this! since this is the main purpose of this lens, large blur circles wide open.

The small cut out for the Nikon camera aperture arm can be seen at 2 o'clock until 7 o'clock... nothing to do about that...
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Details! How did you mount the RF coupling arm to the Nikon optical block? How did you calibrate the length of the arm? Some of us are salivating at the idea of our very own M-mount Nikkors!
 
The RF coupling arm is mounted with two screws onto a cylinder that is glued onto the outside of the rear lens group.

Rough calibration:
Check/adjust the length of the Nikon F to Leica M adapter.
Check/adjust the length between the M mount surface and the RF arm end, at infinity, compare against correct lens.

Fine calibration:
Check target at infinity - a little closer and - a little further on camera.
Check at 5 meters and 2 meters.
 
Thanks! Hopefully I'll find a well-priced 50/1.2 in the near future and report back on my own mod experience.
 
Awesome. I've always wanted to try this with the 50mm 1.2 ais. I had such a good experience with that lens that I'd love to couple it with the M9.

Well done.
 
Erik Gunst Lund said:
The RF coupling arm is mounted with two screws onto a cylinder that is glued onto the outside of the rear lens group.

Rough calibration:
Check/adjust the length of the Nikon F to Leica M adapter.
Check/adjust the length between the M mount surface and the RF arm end, at infinity, compare against correct lens.

Fine calibration:
Check target at infinity - a little closer and - a little further on camera.
Check at 5 meters and 2 meters.
Click to expand...

Hope you don't mind to answer two questions.

1. What type of glue did you use?
2. How do you know how far the cam should stick out of the adapter in order to focus infinity? If the focus lever inside the rangefinder is fully depressed, does this mean that it is focussed in infinity? I think getting this part right would be the most difficult job.

Thanks in advance for your reply.
 
Nice job. If the lens is accurate at close focus and infinity, it means it's true focal length is 51.6mm.

If you are interested, have a look how I modified an SMC-M 50/1.4 in similar fashion (using Novoflex adapter and Epoxy but my own brass cam):

http://www.rangefinderforum.com/forums/showthread.php?t=113676[

AFAIK, there are 3 of those lenses in use by now.

Last month, BrianS has done a similar modification of an M42 Super-Takumar 50/1.4:

http://www.leicaplace.com/f35/pentax-super-takumar-50-1-4-modified-rf-coupled-m-mount-151

Roland.
 
fti said:
Hope you don't mind to answer two questions.

1. What type of glue did you use?
2. How do you know how far the cam should stick out of the adapter in order to focus infinity? If the focus lever inside the rangefinder is fully depressed, does this mean that it is focussed in infinity? I think getting this part right would be the most difficult job.

Thanks in advance for your reply.
Click to expand...

Gel type cyanoacrylate, you have a few seconds to set it correctly and the press firmly into position for a few seconds more to set it.

Measure any lens with a correct calibrated hard stop at infinity and you have the distance.

No it has nothing to with end stop of the rangefinder arm.

Thanks!
 
ferider said:
Nice job. If the lens is accurate at close focus and infinity, it means it's true focal length is 51.6mm.

If you are interested, have a look how I modified an SMC-M 50/1.4 in similar fashion (using Novoflex adapter and Epoxy but my own brass cam):

http://www.rangefinderforum.com/forums/showthread.php?t=113676[

AFAIK, there are 3 of those lenses in use by now.

Last month, BrianS has done a similar modification of an M42 Super-Takumar 50/1.4:

http://www.leicaplace.com/f35/pentax-super-takumar-50-1-4-modified-rf-coupled-m-mount-151

Roland.
Click to expand...

Thanks! Yep same approach, but 'only' a f/1.4 🙂
 
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