| Author |
Message |
    
Velocity
Tinkerer
Username: Velocity
Post Number: 2
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 24, 2009 - 07:47 pm: | 
|
Hi all,
I have a Meyer-Optik 400mm. These were made in such a manner that the rear cone, containing the lens mount, can be unscrewed and swapped with another lens mount if desired. The trouble is that I can't for the life of me unscrew it. I've tried having another person hold the body and we both attempted to turn it in opposite directions, but still no go. Furthermore, I can't think of any tool that would allow me to hold it down and provide enough torque to unscrew it - at least, I have no such tool.
Much as I'd love to get some WD40 and try to spray it into the crevices, I've heard that WD40 should never be used on lenses even if it won't be near the glass elements. Can anyone provide some other possible solutions? I'd really appreciate it! |
Ethostech
Tinkerer
Username: Ethostech
Post Number: 114
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 24, 2009 - 09:33 pm: |
|
I am not familiar with the particular optic but I suspect that since its is, or can be, coupled with an M42 screw thread which is a normal right hand thread, the mount to the optic may in fact be a lefthand thread. German manufacturers in their near paranoid commitment to engineering practices tended to use lefthand threading on one of the components whenever such cascaded component was at risk of being unintentionally unscrewed. Try the same muscle-power as though intending to tighten the mount. Maybe this will release it But if not, no harm is done. |
Velocity
Tinkerer
Username: Velocity
Post Number: 3
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 25, 2009 - 07:31 am: |
|
That's an interesting idea. The front element and the lens hood both screw on in the normal right-handed manner, so I hadn't considered that, but it's quite possible. I'll give it a try - if nothing else, perhaps it'll loosen something up a bit enough to fully unscrew it. I'll report back on how it goes. |
Lucas
Tinkerer
Username: Lucas
Post Number: 91
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 25, 2009 - 12:34 pm: |
|
I have a Meyer 200mm for Exakta and that is a normal righthanded thread to release the ring and get the cone off. I had the same problem with a Pentacon 4/300 and ended up clamping it in a vise with cork ( stolen from the kitchen, normally used to put hot pans on) to protect the lensbarrel, using bicycle inner tire to get grip on the ring and ultimately brute force to unscrew it. I would first check if there is not a little grub screw somewhere in the ring to secure it. |
Bossman
Tinkerer
Username: Bossman
Post Number: 45
Registered: 02-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 25, 2009 - 10:56 pm: |
|
I have dealt with every imaginable seemingly impossible "stuck" ring, lens, barrel or whatever. When all else fails, I try using one of my punches or sharpened shafts and after using a small drop of penetrating oil or even amonia, start tapping and tapping. I usually scribe the two parts so I can watch for the slightest movement and get encouraged!! Keep on until it loosens (may take quite a while)!! |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 156
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 26, 2009 - 02:49 am: |
|
I take it this is a Telemegor? There doesn't seem to have been a 400mm Orestegor according to my searches. The long Orestegors had interchangeable mounts but I don't think the Telemegors did.
On my 300mm Telemegor the rear outer section is purely cosmetic and can be unscrewed, leaving the mount attached to the lens. The mount can then be removed after taking out 3 screws. |
M_currie
Tinkerer
Username: M_currie
Post Number: 170
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 26, 2009 - 07:47 am: |
|
If I am reading the description correctly, this is a T mount lens, with an interchangeable mount. T mounts have tiny setscrews in them to prevent the lens from unscrewing from its mount instead of coming off the camera when you twist it. Is it possible you did not find the setscrew or setscrews for this? Before applying any more force, I'd look again for missed setscrews. |
Velocity
Tinkerer
Username: Velocity
Post Number: 4
Registered: 03-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, April 09, 2009 - 12:27 pm: |
|
Sorry for not replying back sooner. I've resolved the issue! I took some pictures and can upload them here if anyone would like, but basically what you'd need to know is that there are six very tiny screws along the base of the cone (the part that connects with the body - specifically, they're along the part with ridges that you'd instinctively grip to start turning). They're evenly spaced along it, but three are a bit more toward the top and three are a bit more toward the bottom.
Unscrewing the bottom three will allow the lens to unscrew relatively easily. It'll become clear why it should be easy and not require a lot of initial force once you get to screwing it back on (which I'll also detail). The bottom three are what connects the mount to the main body. This is what I was after, and if you're reading this with the same issue I had, this is what you want, too. Don't unscrew the top three. Unscrewing the top three without unscrewing the bottom three will allow the lens mount to rotate while still connected to the barrel. Unscrewing all six screws will allow you to pull the ring off, but that's it - the lens mount itself stays in one piece.
Now, how do you put it all back together? First, make note of where the holes for the screws are - either make a light mark to indicate, or something along those lines. Screw the lens mount back to the body. If you screw it as far as you can, you'll overshoot the holes for the screws. Unless someone did improper work on your lens, the end cone should never be screwed as far as possible (not even nearly!) and for this reason it should always be relatively easy to unscrew the end cone (unless there's some gunk built up). Don't be deceived - if you tighten the screws enough, then even if they're outside of their holes it'll feel like the cone is relatively secure (but probably not as secure as when you started out, assuming that the screws were properly set in the first place). If there's still a bit of play, lightly loosen the screws, lightly turn the body or the top while gently applying pressure to the screw in the turning motion - with a bit of luck (and sensitive fingers), you'll be able to find the hole that way. Go ahead and screw it back in. You would use a similar method if you unscrewed the top three screws.
For reference, I used a flathead screwdriver that was size 01 (I believe). My size 02 was too large, but in reality it seems as if a "size 1.5" would have fit just right. Also, one of the two lens bodies had screw holes that seemed a bit damaged, and I could see that the screws had been dragged along the main body's screwing threads a few times - so don't unscrew the screws to the point that they come out (which would be a pain), but do make sure to sufficiently unscrew them.
Steve_s: This is indeed a Telemegor. This one came in three flavors of lens mount: Praktica (FX breech-lock mount), Exakta (bayonet mount), and M42 (screw mount). The ending cones can be swapped 
M_currie: As mentioned to Steve, this lens came in M42, Exakta, and Praktica lens mounts. But as both you and Steve mentioned, it was a matter of having to unscrew smaller screws before being able to unscrew the mounting cone.
I do have pictures showing the screw holes for both the upper and lower screws (screw holes on the cone and on the lens body); if anyone would like to see them posted, let me know! If I have the time and remember to do it, I'll repost with them anyway. |
|
