Nikon rangefinder lens focus way off.

darinwc · Sep 24, 2015

I bought a Nikon s2 online. Everything seems to work. But it seems that something is wrong with the lens. I removed the lens unit from the barrel so I could clean under the rear element.
When I removed the lens barrel from the mount, a wire fell out. It was in the shape of a C but only barely more than a half circle. Also, it was made of something closer to soldering wire.
So, is it normal to have a spacer in the lens mount? What does it usually look like and what is the property thickness?

Xmas · Sep 24, 2015

darinwc said:
I bought a Nikon s2 online. Everything seems to work. But it seems that something is wrong with the lens. I removed the lens unit from the barrel so I could clean under the rear element.
When I removed the lens barrel from the mount, a wire fell out. It was in the shape of a C but only barely more than a half circle. Also, it was made of something closer to soldering wire.
So, is it normal to have a spacer in the lens mount? What does it usually look like and what is the property thickness?

Please clarify you removed the /2 or /1.4 lens from the cameras internal bayonet?
And then removed the lens cell from the lens outer barrel?
Some of the Soviet lenses are shimmed others are held on grub screws...
I'd expect a shim to be flat aluminium or brass and a complete circle...
But it may have been re- shimmed for calibration, you should test at 2m and 8m with a ruler at 45 degrees to optical axis.

Sirius Glass · Sep 24, 2015

The wire sounds like a C ring that is used to retain the rear element. You might want to send it to Carol at http://flutotscamerarepair.com/ I have been happy with her work and her prices.

Xmas · Sep 24, 2015

The Nikon, Zeiss and Ukranian lenses elements are all on screw thread lens rings... Not seen a c ring on any of them yet...

darinwc · Sep 24, 2015

Guess I should have started with the pics. It's a F 1.4 Nikkor.

blind_sparks · Sep 24, 2015

Looks like some sort of homemade shim/spacer to achieve the proper back focus for the lens - definitely not original. Perhaps the last owner took it to pieces as you have done and lost the original shim(s). I would personally use a bit of tape (or, if you have one handy, a ground glass) and check the focus at the film gate with the camera on B/T. Compare it to what the rangefinder is indicating, if the RF is seems properly aligned...

As far as proper thickness for shims goes, it will be trial and error. The 1.4 Nikkor is optimized for close-up, so you may want to try to achieve best focus at the closest indicated range. You can create new shims from foil, paper, or some sort of thin stock if needed. Some shims I have seen are so thin they're hard to handle. You can also have any competent tech do it too.

I would guess that that wire is probably way too thick, though. Good luck!

leicarfcam · Sep 24, 2015

Here is a Nikkor rf lens taken apart but it looks like this part is not part of it.

http://www.nicovandijk.net/rflensrepair.htm

Xmas · Sep 24, 2015

Check the body first...

http://www.rangefinderforum.com/forums/showthread.php?t=118734

darinwc · Sep 24, 2015

leicarfcam said:
Here is a Nikkor rf lens taken apart but it looks like this part is not part of it.

http://www.nicovandijk.net/rflensrepair.htm

Ah perfect! so that confirms that the the ring spacer on mine is not original.
Well I tested the lens with and without the spacer with the camera set on bulb, using a focus screen.
With the wire spacer, the focus is just about right. And without, very wrong.
I will have to construct something better than this hack. Though I cannot find my micrometer right now..
So thanks for the info. Very helpful.

leicarfcam · Sep 25, 2015

darinwc said:
Ah perfect! so that confirms that the the ring spacer on mine is not original.
Well I tested the lens with and without the spacer with the camera set on bulb, using a focus screen.
With the wire spacer, the focus is just about right. And without, very wrong.
I will have to construct something better than this hack. Though I cannot find my micrometer right now..
So thanks for the info. Very helpful.

As thick as the ring is that tells me someone disassembled the focusing helicoid and did not reassemble it correctly. There are a number of ways the helicoid can screw back together but it needs to be put back together with the correct threads (lands) together. Instead of making the wrong shims you need to get it fixed right..

I've never seen one in 40 years of servicing cameras with more than a couple of thin shims..

darinwc · Sep 25, 2015

leicarfcam said:
As thick as the ring is that tells me someone disassembled the focusing helicoid and did not reassemble it correctly. There are a number of ways the helicoid can screw back together but it needs to be put back together with the correct threads (lands) together. Instead of making the wrong shims you need to get it fixed right..

I've never seen one in 40 years of servicing cameras with more than a couple of thin shims..

Well I'm not sure if you are familiar with this mount or not, but there is actually no focussing helicoid in the lens at all. The helicoid is actually in the camera, and it moves the whole lens.
I have tested the camera and the rangefinder is correct and with two other lenses and everything else is correct. (i dont have another 50 f1.4 nikkor to check with though)

I checked the lens with the wire shim at both infinity and at about 6 feet, checking against the rangefinder and a ground-glass.

So it is pretty clear that the spacing is right for the lens and the spacer is required for proper focus (may be off by a hair, need daylight to check better)

leicarfcam · Sep 25, 2015

You are correct. I was thinking about something else. But I stand beside my assumption that something has been misaligned possibly by someone who did not know what he was doing or else a part is missing. You might also check the focus helicoid on the body..

Years ago people would have their Contax or Nikon lens modified to work on the other which meant alignment issues if trying to use on the original model without undoing the job. There wasn't much difference. If I recall the difference was only about 1mm which is enough to affect focus.

darinwc · Sep 25, 2015

Yes, the lens will probably need to be properly aligned. Unfortunately I dont have the tools to do that. So eventually I will have to decide to shoot with it as-is, get it properly serviced, or resell as-is (with proper description, unlike the person I bought it from).

Xmas · Sep 25, 2015

Just put it back together if it focuses accurately a good worker has rebuilt it.

I'd only note that Nikon and Contax lenses will interchange but not focus accurately when swapped.

Except some Nikon lenses have a 'C' on the barrel which means they were ment only for contax cameras, but I'd doubt that some one would have bodged that.

darinwc · Oct 7, 2015

Update: The focus was off slightly even with the wire ring that was in it. I bought some different gage piano wires and I found a 1.2mm wire has the most accurate focus. -I will provide another update when I get some film through it. Yay!

Nikon rangefinder lens focus way off.

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