Contax 139Q and Aria: mirror stop adjustment?

[Fernando2]

Hello everyone,

I just bought a Contax 139Q and a Contax Aria, used but clean.

Unfortunately, both have focusing issues (increasing backfocus at increasing subject distance), confirmed with Lens Align Tool and viewfinder magnifier, with all my Zeiss lenses.

From past experiences, I think the culprit is the mirror rest position (mirror stop).
I've read that, at least in the 139Q, the mirror stop position (a small protunding "thingy") is adjustable, precisely to correct focusing errors.

Does anyone know how to do that? I have tools and some ability, but I didn't found directions nor tutorials about adjusting the mirror stop.

If anyone could help me, I would be really grateful: it's frustrating when you have a "new" nice camera and can't use it. 🙁

Thanks 🙂

Fernando

 

[Ranchu]

I'm curious if you ruled out the focusing screen position? That's a lot more common. To fix it you add or remove shims, mylar/ polyester film works OK, but all the tolerances are really fine, so you might search a while before you find something the perfect thickness.

I don't know those cameras, but often the stop has some kind of 'cam' action, where the post it turns on is off center so the bearing surface position is moved as it turns. I've only done it on a D200 (****ing Nikon) and very very small changes were necessary, almost trial and error back and forth because getting the screw moving actually moved it too much. But I did get it correct after all that. It's a lot easier on a digital camera as you might imagine.

 

[Fernando2]

It's not the focus screen; yes it's more common but has a different effect.
Yes, indeed on DSLRs is so much easier! I had a similar issue (focusing screen offset, that time) on the Canon 5D and adjusting was easy enough since you can check the adjustments almost in real time. 🙁

I've found that the 139Q has two screws to adjust the mirror (offset and rest angle) but I'm afraid they are internal. That is, I'm supposed to open the camera.
In this case, I'll just have to throw it away: a repairman would ask more than the value of the camera. 🙁

 

[valdas]

How significant is the backfocus? Is it visible only at wide apertures or stopped down as well?

 

[Fernando2]

It's quite significant, about 10% error.
If I focus to the nearest eye of my subject, I get the other eye sharp. I often shot wide open (I have nice glass) so it's very irritating.
I know it's the camera because I did extensive testing with various charts, including the Lens Align Tool.
And I know it's the mirror because on the Contax (Canon is different by the way), the focusing screen is not shimmed: plane of focus adjustment is done entirely by the mirror adjustment (2 screws: offset and angle).
Too bad they are not accessible with the camera fully assembled. 🙁

 

[farlymac]

How internal are they? If you can access them from the bottom, that's not too bad. Accessing from the top is a little more difficult, only in that one has to make sure to align any dials in the proper manner on dis-assembly and re-assembly. But if one needs to have the mirror box out of the camera, that's a major tear-down.

PF

Okay, just looked at this site http://www.contax139.info/repairs.shtml and it states that the mirror box must be removed for the adjustment. But it also says there is a rubber or plastic bumper on the stop that can fail, which results in focusing error. Have you checked the stop to see if the bumper is damaged, or missing?

 

[j j]

Okay, just looked at this site http://www.contax139.info/repairs.shtml and it states that the mirror box must be removed for the adjustment. But it also says there is a rubber or plastic bumper on the stop that can fail, which results in focusing error. Have you checked the stop to see if the bumper is damaged, or missing?

Peter from contax139.info does a great value restoration on these cameras. I bought one from him. It is very smooth in use and he did a nice re-cover job on it. He buys 139s to restore them so Fernando if you decide your camera is junk he might give you a few euros for it. It would be a shame to throw it away.

 

[Fernando2]

Peter from contax139info (very kind; a really nice guy) confirmed that the mirror box must be extracted to adjust the mirror. So it's a no-go.

@j-j: The issue is, I'm in Italy. Sending stuff outside EU is very costly (well, even sending stuff outside Italy is quite costly).

Regrettably, this camera may end its life as a "demo body" for photography lessons (how a shutter works, etc.).
I would not actually throw it away, in any case. I don't have the heart to throw away any camera (and in fact I have plenty nonfunctional cameras around here) 🙂

Thanks for your support, fellow RFF users.

Fernando

 

[j j]

Life as a demo camera is much better than in the trash! By the way, Peter lives in England.

 

[mdarnton]

I "fixed" a similar problem in a different brand camera by layering plastic electrical tape on the back side of the mirror where it hits the stop.

 

[Fernando2]

Peter from contax139info (very kind; a really nice guy) confirmed that the mirror box must be extracted to adjust the mirror. So it's a no-go.

Follow up: I ended up purchasing a 139Q from Peter (contax139.info).

He accurately refurbished one of his 139Q bodies.
I asked for a little more work (and agreed to pay a small extra, of course, at the very least to repay him of the film for the test shots!) and he took care of calibrating the mirror at short and long distances (well, within reasonable terms of course).
He found a good compromise between long and short lenses, long and short distances.

The camera just arrived, and it's BEAUTIFUL!!! 😀
To my eyes, it's even better than new!!!!

My old 139Q will serve as a learning tool for beginners, which is a nice way to gracefully close a career in my opinion. 😉

So, happy ending. Thanks to everyone for the support!

Fernando

 

[j j]

Good times!