Nikon 500mm f/8 Reflex-Nikkor (New) tripod collar issue

[Jim Covello]

Hello, everyone! I was hoping someone could help me. I used to have one of these lenses that I bought new in the mid-1980s and then sold in late 2000s, largely because I could never focus the thing and I wanted to help fund a 70-200 instead. But I missed it, even though I have a 500/5.6 PF (a truly amazing lens in every respect). I figured that I could successfully focus one with a zoomed EVF, so I picked one up on ebay and it showed up yesterday. The glass is pristine, the lens case is in pretty good shape, the little case that holds the extra 39mm (I think) rear end is completely crumbling to pieces (which is odd), and the back of the lens has one tiny nick on the metal. But something is wrong with the screw that tightens the tripod collar. The collar has detents every 90° that work fine, but screwing in the knob should lock it into place and it doesn't—it basically has no effect and you can always twist the lens out of the detent with the same amount of pressure. So, I am not sure what happened there, but was wondering if anyone knows how that might be fixed. I am not sure how to get the tripod collar off in order to look at the inside.

I haven't posted any pictures of the lens because there's not much to see and anyone who knows what to do probably has one, but I can post a picture if needed. Any insights are appreciated!

[Bob.S]

I don't know this particular item at all and have never actually seen one 'in the flesh', however 30 plus people have read your post and there is still no answer so perhaps I can at least get things moving.......      If you have to 'screw' something to hold it firm and this is not possible then there is a major chance that one or the other parts of the thread is stripped,...ie., the pitches are so damaged that theycan no longer pull tight against each other.    The remedy is to disassemble the parts and replace the threaded parts with new threaded parts preferably made with better  more durable threads....threads usually fail becasue they are either too soft or too small for purpose.    Stainless steel threading in the form of bolts, screws, nuts and studding is now widely available and cheaper than it has ever been.

I see that you are an engineer, however, might I suggest that you show the item(s) to a good 'mechanic', someone like a plumber, automotive fitter, washing machine repairer, clock maker, model engineer, or a neighbour seen to use tools etc. and they will almost certainly be able to work out how the parts disassemble and how better stainless threading might be fitted.

[Nasos Kosmas]

Pictures please

[fish_shooter]

I have the same lens with the same problem except that there is a little bit more friction with the knob tightened. But not enough to stop rotation. My solution is to mount my rig when using this lens on a tripod from the camera. The lens is so light weight that I doubt there is enough stress put on the lens mount or adapter to worry about.

[Jim Covello]

Thanks for the responses, everyone. I have attached some photos. The screw does not appear stripped, because it clearly threads in and out. I believe that the actual detent is under the black screw on the tripod foot. Someone clearly messed with that screw with the wrong screwdriver because it is a little chewed up...nothing too egregious, though. My suspicion is that there is supposed to be a friction pad or something under the little black screw know that for some reason has been lost (or crushed or whatever). I suspect that what I need to do is remove the six little screws around the periphery of the back and then some pieces will come off and free the tripod collar, which is a one-piece affair. Before I do this, though, I would prefer to know that I won't be disassembling actual optics.

It is in the category of an annoyance at worst, but I would like to fix it if I could.

[Bob.S]

Some observations in no particular order;

1) The "detent" must indeed be under the damaged screw adjacent to tripod bush......for the lend to turn the detent must be spring loaded.    If this spring becomes weak or is of low temper/quality then the detent would NOT lock adequately in use.    Perhaps removal of the damaged screw using the right size screwdriver might give some useful discoveries.

2)  To remove the tripod collar entirely from the lens do NOT remove the "six little screws" on the lens backplate as they look to me like the holding screws for the rear mirror housing...instead;......

3) pay attention to the v. small cross slot screws in the sides of the rear barrel imediately behind the tripod collar....you can see one clearly in your second from last photo, close to tripod foot.    Carefully remove or loosen these and see what happens with that barrel flange...does it loosen against the tripod collar...?

Hope some of this helps!

[Erik Lund]

This lens has obviously been looked at before, the the screw next to the tripod mount threads has clear marks, from the wrong size screwdriver,,, It holds the spring and ball for the indent stops.
Yes you need to take the rear off if the lock screw doesn't come out by itself, there usually is a brass 'disc' the screw press down on.

[Jim Covello]

Thank you very much, Bob and Erik! That's the sort of advice I was looking for. I need to procure some appropriate screwdrivers before I tackle this.

[Erik Lund]

Rick has a lot of very useful information on Nikkor lenses;

https://richardhaw.com/lens-repair-articles/

Some of the lens design details are similar so you might be fortunate and find out how to take the lock screw out and repair the lock disc
I have a dissembled Nikon PN11it has a similar lock screw, I'll have a look,,, It's modified for an extension tube made out of TC20E so no clue how it was originally,,,

[Erik Lund]

Here is link to short description of how to get the Lens collar off

https://www.dpreview.com/forums/thread/2693833

Here are the major steps. 1. Remove the tripod mount, which is held on by two screws. 2. Remove the rear retainer ring, which has three screws holding it. This ring has a withe arrow and is just below the ring with the focusing scale. 3. Remove the focusing scale ring, which has three screws. 4. There is a focusing delimiter with two screws.  5. Remove the long focusing ring, which is held on by six screws. 6. Unscrew the rear cell. As I noted, be sure to use tape to mark alignment points.
You don't need to go too far of course,,,