Need instructions for repair Nikkor SC 50/1.4 LTM

[kawabata]

Hi,

I got a Nikkor 50/1.4 LTM whose optics are in nice condition.

The annoying thing is that a ding on the outer edge of the back ring (the piece with the screw mount) makes this ring touch the foucusing ring and prevents it from moving freely. Thus focusing is very difficult.

So one needs to take this ring of, rebend slightly the outer edge. I hope that then everything will be fine.

So I would like to find instructions on how to remove this back ring.

Any help ?

Some (horrible iphone) pics are here :

http://bmpw.free.fr/nik/

The ding is visible near the 3.5 feet focusing mark. I added views of front and rear to make the lens model clear.

Thank you !!

 

[Platinum RF]

Not very clean, can you post a better quality picture and indicate when is the dent?

 

[Spavinaw]

I can see the dent in the picture OK. This may be a long shot, but I looked at my lens and I was able to get just the tip of an X-Acto knife blade between the ring that is bent and the lens body. I realize the ring that is bent is very sturdy; however, you only need bend it a teeny tiny amount so it doesn't rub (if you want to take the dent out completely you'll probably have to take the lens apart). So, perhaps by working with the tip of a thin knife blade in from each side of the dent you could bend it just enough to get some clearance. Above all, do not get the blade jammed in and then break it off.
I think an even better idea would be to get a very narrow, very sharp chisel (or equivalent) that you could hammer on. Then start on each side of the dent and work your way in. You might could get nearly all the dent out this way. Good luck.

 

[kawabata]

Thank you. I will send a better pic very soon.

I did try to correct the dent without dismantling, but the lens is sturdy indeed, and there is very little room.

There is no big hurry, but I would like to use the lens one day :-/

 

[kawabata]

I added better pictures on :
http://bmpw.free.fr/nik/
(with an ugly fingerprint 🙂)

I did try to bend the piece, but there is little room for inserting a strong enough tool.

Trouble is I have so little time these days, and dismantling such a lens is better done in a quiet mood.

I found an older message of Brian Sweeney, saying that one can unscrew the optical body after removing a back holding ring. But the only ring I see seems to old just one optical element.

 

[kawabata]

OK. So I finally did make the lens work the ugly way, by rebending the ding with a solid screwdriver.

So now I have an exclusive lens in my LTM stable. I does make nice pictures indeed, although I am not sure there is much progress wrt my Jupiter-3 actually 🙂

 

[puderse]

50mm RF lens

50mm RF lens

The Tomosy NIKON book has instructions for disassembling a NIKKOR-HC 5cm f/2 RF lens if they are close to the same lens construction. Don't have an RF but I have the book and a few NIKONS.

 

[menos]

I think, this comes too late, as the sledge hammer and and laser has been taken to work already, but here it goes:

To get to the LTM mount, first, you have to separate the optical cell from the focussing mount.
In one of your last pictures, you can see the black retaining ring, that holds the optical cell in the focus mount.
Use a lens spanner and turn it CCW to loosen.
Now you have the focus mount separated and have to go the lens spanner way on the retaining rings inside, to separate the LTM mount entirely.

Post pictures, as you go ;-)

 

[johannielscom]

Today I fixed the serious wobble in my Nikkor 1.8/35mm LTM, after seeing what the rear end of the 1.4/50mm looks like.

I figured the optical cell of the 18/35mm would be fixed in the focus mount in an identical fashion, and I was right.

To get to the ring that holds the optical cell in the focus mount, you first need to remove the rear element. It simply unscrews counter-clockwise, but be sure to have clean hands and clean off all grease and dirt from the lens mount and the exposed helicoid, since there is very little room around the rear element and you will grip onto the flat element surface. don't want to scratch it right? After all, this is a lens that easily is > USD 1,000 since only 1400 LTM Nikkors 1.8/35mm were made and a nice-condition one is a great shooter and a great collectable piece in one...

Once the rear element is off, you can see the retaining ring with two notches for a spanner, but there is (again) very little room. I used a the point of a sewing needle to lodge into one of the notches, and loosen the ring further, small taps on the needle end with the closed beak of a pair of small pliers.

I had to make sure what was in the focus mount and see if nothing else needed tightening there, so I undid the ring completely and lifted the focus mount off the optical cell.

Inside, everything was peachy 😉 and this is what it looked like once taken apart:

To the left you can see the tiny ring that fits the optical cell into the focus mount, and the rear element is leaning up against the keyboard.

It turned out that the ring was all that caused the wobble in my lens. I re-assembled the lens: put the focus mount over the optical cell (fits one way only, no slack at all: great engineering!) and dropped the cleaned ring into the narrow space between the cell and the mount. Used the needle point to move it around until it gripped, then held the needle stationary and rotated the lens (much easier and faster to get the ring back into position this way).

Once it did not go any further than that, I used the pliers again to lightly tap the needle's rear end, needle point in the small notch on the ring. Did this with both notches, several times. No slack or play or wobble remained, except for a 1/3mm bit of play, likely in the focus mount but not between mount and cell.

Screwed the rear end back on and gave everything a (very careful) clean.

The lens feels as tight as the day it left the factory, I reckon 😀 😎

 

[johannielscom]

Posted this post to my website as well, as an article on how to do it.

For future reference: www.johanniels.com.

 

[ZeissFan]

Any time that you disassemble a lens, you should check infinity focus. And you have to be even more precise with a wide angle lens.