Nikkor-N 24/2.8 Auto loose focus ring - fixes?

[Scott]

Hi, all -

I knew this lens had a loose focus ring when I bought it, but I want to see if I can't rectify the situation.  Ring has about 3/8" play either way in it.  Is there a simple way to take up the slack?  Any ideas?

Thanks,
Scott

[epatsellis]

The only way is to tear down and clean/regrease. I had a hassy 80 that had the opposite problem, I had to disassemble, lap and regrease, it's smooth as silk now. (hopefully, I'll have a camera to use it on again soon.)

[Scott]

Well, getting into it seems the only way.  I've got the front trim ring removed using a black rubber stopper.  Inside is a set screw and two points for a spanner.  Hmm... :eek:

[Scott]

Used the Spanner to remove the front group:



Now, there's a setscrew (on the right) and some little round pivot-like thingy (on the left):



There's also a setscrew in the focus ring itself:



Removing any of these has no effect on further disassembly.  I'm at a loss and don't want to make things worse.  I have an SOS out to Rick Oleson; in the meantime, anyone have a clue about this?

Scott

[epatsellis]

Remove the mount and rear element, there will be two screws under the aperture ring or facing the rear mount deeper in(if I remember right) that hold a brass "key" that keeps the helicoid from rotating, remove the key and it will unscrew totally, be sure to scribe witness marks, unless you enjoy the frustration of realigning the helicoid several times til you get it right.

[Scott]

Well, Rick Oleson hasn't worked on this style Nikkor.  And a posting at KYPhoto supports Erie's idea.  But the slop, according to that post, and as a logical extension of the design Erie alludes to, is due to wear in the key and/or the keyway it fits.  Neither of which is anything I can fix, short of making a new key.  I might pull the mount off and have a look-see, but I'm guessing I'll just have to live with the excess play.  Still has infinity and close-up, so it's really an exercise in nit-picking, anyway. :p

[epatsellis]

Scott, some of the Nikkors allow you to adjust that play, depends on the individual design I think. At the very least, disassemble enough to get access to the helicoids when fully extended and add a little grease (I use a very light Moly lube, though there are some silcone based greases that others have used well) it doesn't take much to eliminate alot of the slop and too much will go from sloppy to hard to turn.

Take the mount off and take a look, you may find that there are elongated holes for the key. Only takes a few mins and while you have the aperture ring off, you can clean it well and lube it. There's no detent spring, just a metal spring piece for the detents, if the detents are soft, you can sharpen the embossed detent to firm them up.

[epatsellis]

Scott,
Looking at one of my scalloped ring lenses, if you extend the helicoid all the way and grab the middle section and the outer section, if there's play in the "key" you will feel it between those two, if it's helicoid wear, and the need to pack it with a little grease, it won't be between those two. I have used an interesting product from Dupont I found at Ace, it's a dry film, teflon bearing lubricant, works great with helicoids that aren't worn and gives you that effortless Nikon feel. If you need to make up some slop in the helicoids, find the lightest grease you can, Nikkors seem to prefer very little (a few swipes across the threads) and worked in. It's easier to work up from too little than too much (requires a good flush with contact cleaner if you do, sans optics, of course). Good luck and let me know if I can help more.

[Scott]

Thanks for the description, Erie.  You're about the only person who's heard of this, 'sides from one guy on kyphoto.

Okay, when I unscrew the mount, it snaps to the counter-clockwise.  Spring-loaded.  Seems to operate the aperture.  I'd hate to pull the bottom off this thing and lose it's functionality altogether...  :eek:

[epatsellis]

No worries, it will be obvious how it goes back together when you get it off. basically, it springs down to whatever aperture is set on the ring, some use a tapered ring, others some odd linkage, but all I've encountered go together simply enough.

[Scott]

Okay, Erie, I'll give it a shot.  But first, the seal kit came in from Jon Goodman today.  I've ordered several of his kits, and they're absolutely top-notch.  Great materials, precut, and detailed camera-specific instructions.  WOnderful stuff.

Anyway, the new seals are in.  Most impressive is the function of the new mirror bumper.  Silent and soft now.

So, I'm loading the camera up now, and am testing it out.  Tweaking the 24/2.8 will be later. :cool:

[Jim Evans]

Just found this thread.   Keep us posted on the 24mm.   I'm curious to see if the slack can be fixed. 

What kind of Bozo would sell you a faulty lens anyway!   :rolleyes:   :p

[Scott]

The same kind that would sell me an ugly user 55 micro...

[Scott]

Well, just took my first shot with this camera - a grab shot of the storefront of the local Ace.  The meter seems right on (agrees with Sunny f/16, anyway), the lens popped right into focus, and everything worked.  Feels wonderful to hold - has enough heft to it to make it stable, without being so much that it's burdensome.  I think I'm going to like the camera as much as my trusty Spotmatic.

Now, the proof'll be in the pictures, obviously.  Going to run off the roll tomorrow morning, give CVS another try for developing and scanning, and we'll see what happens.  But I love the camera so far, and the 24mm perspective is addictive!

If there's time this afternoon, I may break open the 24's rear and see about tightening up the focus, but I didn't really notice it in use.

[Scott]

Well, I pulled the back off this lens.  Can't see anything, with or without the rear group, that looks/feels loose.  I see the little key and prong which hold it, and that's all tight.  I think this lens needs more disassembly than I want to do right now...