| Author |
Message |
    
Ron
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 23, 2005 - 01:52 pm: | 
|
I have just cleaned the lens (fungus) of a pretty Zeiss Ikonta 521/2 folder and, like a dummy, did not note what I was doing when I removed the focus ring to get to the front element. The glass is now sparkling...but is there someone who knows the precise method to re-assemble? I thought I had it, only to have the lens fall out before the focus reached infinity! Now the lens assembly is in so tight, the focus ring is VERY hard to turn. PLEASE HELP! |
rick oleson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, April 23, 2005 - 08:42 pm: |
|
i don't have a 521/2.... doesn't this front element just screw in and then have a focus ring that slips on from the front and get fixed in place by set screws? on most cameras of this type, i set the lens to infinity by focusing on a groundglass in the film plane and then attach the focus ring in the infinity position and i'm done. |
Mike Kovacs
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 09:02 am: |
|
Are you saying that the lens suffered impact damage and now it focuses tightly? If so, the focusing threads have been knocked out of round by the impact and there isn't a whole lot you can do to fix it IMO. |
Winfried
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, April 25, 2005 - 01:24 pm: |
|
The helical threads must be absolutely clean, i.e. without dust particels or dirt. Both parts fit together very tightly, since there is not much play allowed in an optical system. It may also happen that you slightly damaged the 'entrance' of one of the threads (there are several threads cut in parallel) when trying to fit both parts together - it does not take too much force to deform a fine pitch thread cut into brass.
You can try to scrape the 'entrances' of the threads with a small screwdriver blade. It is also possible to re-cut the threads with a so-called thread chaser tool, but such a tool is hard to find, and the threads must have an 'even' pitch of 0.5/0.75/1.0mm. |
Ron
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 26, 2005 - 08:40 am: |
|
No impact damage...the lens fell into my hand! The front element DOES just screw in, and the focus ring attaches by set screws. I thought I done all this properly, but the lens "unthreads" when I try to focus, and falls out (with the focus ring attached)...and I cannot figure out what I am doing wrong! (must be some of that "old-timers" disease creeping in)! |
Tony Duell
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, April 26, 2005 - 01:42 pm: |
|
The 0.5mm and 0.75mm pitch chasers are useful for cleaning up filter threads if you drop the lens onto the front. I've never met a focussing thread with as fine a pitch as that, and most times focussing threads are a square (acme-like) profile, not the more triangular profile of other threads.
If you've got nothing to lose, you could try putting a bit of fine valve grinding paste (sold for seating the valves in a car engine) onto the threads and working them back and forth. I would only consider doing this if I could remove everything else from the focussing mount (i.e. remove all the optical elements, leaf shutter, etc). If that griding paste gets onto an element, or into a shutter, it will do untold damage!
Of course you also need to clean the paste off very carefully when you've finished. A good degreasing solvent should shift it. |
Roger Provins
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 27, 2005 - 11:03 am: |
|
There must be a close focus stop of some sort. Have you lost/forgotten a set screw which comes up against a fixed stop on the shutter body? |
Alex
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, May 15, 2005 - 04:51 am: |
|
I suspect Roger's right. I don't have a 521/2, but I have a few other Ikontas, whose lenses I've disassembled for cleaning and regreasing. There's often an 'infinity post', a small pin which screws into the side of the focussing lens rim, so that when you are screwing in it will butt up onto a fixed post on the main mount to stop you screwing the lens in too far, and likewise at the other end of the focussing lens's travel, butts up against the fixed post on the other side to stop the lens unscrewing right off the camera. Usually you have to take this post off the lens in order to get the lens off, and then put it back once you've got the lens back on. I wonder if this post had gone missing before you started work on the camera? |
