Zeiss Contessamat SBE sticky bits

[johnnyrod]

Time for me to seek some advice. I'll give an intro but you can skip to the last paragraph if you like. I bought a Zeiss Ikon Contessamat 35mm fixed lens rangefinder last year, in fact it is my first ever rangefinder. I shot a film and was disappointed to find that the focus distance seemed right, but nothing was sharp. One flashlight test later and you could see blooms of fungus on all lenses. So I put it to one side and this weekend have pulled it out again to have a go at.

This camera operates in manual or shutter-priority mode via a (working) selenium cell. The aperture blades are slow to retract, and the shutter runs noticeably slow on speeds like 1s, 1/2s etc. I tested the speeds of the faster ones (it goes up to 1/500s) and these were about 2/3 what they should be i.e. also slow but not too bad. Add that to the fungus, and also that this is quite a complex beast, not just having auto aperture but also some gubbins that, if you set the GN of a flash, will alter the aperture with focal distance accordingly. So I put it to one side for when I was feeling bolder.

I've got it in a million bits right now, and have removed the fungus. I have the shutter/aperture plate and have cleaned the blades of each as best I can, so now they appear to be free of oil. The aperture snaps back and forth easily - maybe the problem (if any left) is in the parts outside of that. The shutter seems to snap open and shut quickly - I haven't re-run the tests on the faster settings yet. The slower ones though and the self-timer run very slow - the latter can stall - and it seems to be in the gears etc. that are whirring in the gap between the shutter opening and closing. Picture here:
https://flic.kr/p/zUBRev
Self-timer is the chunk in the bottom left, set but the fork at 6 o'clock. All the right hand side is the gear to run the shutter, this is in the same orientation as it is in the camera - at the 12 o'clock position is the shaft that comes in from behind to cock the shutter. The speed setting ring is removed in this pic, and the residues on the blades are gone now. So, if the blades are fine but the mechanisms are sticking, how best can I rectify this? I have access to a whole range of solvents. So sorry for the long post, but please let me know your thoughts.

Thanks a lot
John

 

[johnnyrod]

I found my old data and retested the faster shutter speeds. The original speeds were:
1/500 actually came out 1/280
1/250 was 1/140
1/125 was 1/95
1/60 was 1/43
1/30 was 1/25

Re-running this today I got 1/340 and 1/298 for the 1/500 speed, the other were basically the same. As I think I said above, the blades seem to snap open and shut fairly well, and I tend not to use slower than 1/30 anyway. Am wondering if it's worth worrying about cleaning the mechanism, also bearing in mind the notes on Certo6's site about larger shutters - is it really possible to get the 1/500 speed any faster than it already is?

Anyway please pass some sort of comment about any of this. When I'm done I'll post the pics on Flickr as I couldn't find anything like this.

Thanks a lot

 

[johnnyrod]

Well the latest gripping instalment is... I took the escapement and self-timer out of the shutter, cleaned and sparingly lubed them. It's made a bit of a difference to the slower settings but the self-timer now works reliably. I've got it all back together*, just** need to set the meter linkage right and collimate the lens (front cell focusing).

* this belies the impossible complexity of this thing

** shutter to meter linkage like nothing I've seen. "Just" as in, Lief Erikson said "I'm just popping out".

 

[johnnyrod]

I've finally finished
https://flic.kr/p/z8rUvu
Setting the meter linkage was a barrel of laughs, but now it reads right (it operates in manual or shutter priority auto modes), possibly a little dark (1/3 stop or so) in brighter light but the fastest shutter speeds are still a little slow so it's probably all the same. The 1/30 and 1/60 are fairly accurate and the meter reads right in less bright light.

It has a function to automatically set the aperture for flash use based on guide number, so the focus ring is against the body next to the aperture ring. There is a linkage to the front cell, and it means you can set the rangefinder first then the focus of the front lens. Unfortunately there is a little play in the linkage, and the focus is only about a quarter of a turn from 1m to infinity so I'll have to see if it focuses accurately all the time.

I've got a ton of pictures to sort through so will post the Flickr link when I've done it. Not sure anyone is reading by this point but this has been a really tricky camera so I'm pleased so far, just need the final proof of sticking a film in it.

 

[johnnyrod]

Link to album with various notes:
https://flic.kr/s/aHskn9Gmon
In terms of fungus removal, I took out the middle and rear elements and soaked them in a 1:1 mixture of ammonia and hydrogen peroxide for a few minutes, which worked fine, though I was using 0.880 ammonia (35%) and 100 volume peroxide - you may not get them this strong at the shops. The front element is mounted in the focusing helix so instead I swabbed it with Q tips and the same mixture. I found it was leaving a white haze that did not want to come off with isopropanol or methanol. Some careful polishing with tissue paper (these are lab ones so no oily stuff or funny treatments, just paper) removed most of this but not entirely, leaving a few very small spots instead of the haze. I'm wondering if it's the use of Q tips as I think I might have seen the same thing on another camera (Contessa LKE). The middle and rear elements were just cleaned with paper and are crystal clear. I don't want to mess about too much and I believe the front lens is most tolerant to dirt in terms of image quality so am going to just give it a go. Will avoid the Q tips next time and see how it goes.

Anyway I hope this helps someone whether cleaning fungus, or working on the same or similar camera.

John