New Contax RX + Repair

by Todd on April 18, 2012

In search of a great film body, I somehow got fixated on the Contax RX, and after getting the refund from returning the MZ-S, I found an RX on eBay, along with a Contax-Zeiss Vario-Sonnar zoom lens, the 28-85/3.3-4. The camera is almost everything I want. Big, solid, beautiful. I wish there was a grip available for it, because the heel of my hand does come off the body a little. It’s a small deficiency when I consider everything else the camera does, and also consider that I don’t have that extra grip room on any of my other film cameras (though most of them at least have accessory grips available).

Anyhow, the camera is awesome, and I couldn’t wait to start shooting with it. I went through a roll quickly, the same day I got the camera, and set about developing it in rodinal, as usual. I was quite distraught when I unrolled the freshly fixed film from the reel to find that it had only been exposed across about one-third of the frame. Here’s a sample pic…every frame on the roll looked like this:

This was an especially painful revelation because I could tell from looking at the exposed edges of a few of the scans that this lens is amazing. I had done a fair amount of research before deciding on the RX, and I had read about the “mirror slip” issue which is relatively common among many Contax bodies: the mirror is attached to its carrier plate by, essentially, double-stick tape, and over time, especially when exposed to very warm environments, the adhesive softens and the mirror slips down.

Initially I didn’t think this was my problem. I assumed it had something to do with the timing of the mirror or shutter, and assumed that if the mirror had slipped far enough to hit the lens bayonet, the failure would be obvious and catastrophic, e.g. a shattered mirror. I was wrong about that, and after inspecting the camera more closely I realized that my mirror had slid down the carrier plate by roughly a quarter inch! It was actually banging against the back of the lens, and unable to go up any farther. I had shot an entire 36-frame roll of film like this, jamming the mirror against the lens every time. Doh! Below is a photo of the mirror slipped well beyond its carrier. You can see the smudgy residue of the tape in two strips across the bottom of the mirror:

I emailed several repair shops about this, and they all replied that they didn’t work on Contax cameras, even though some advertised repairs on “vintage gear.” Lying bastards. ;) I also emailed Eric Hendrickson, who is well-known for his work on Pentax gear. I figured even if he didn’t typically service Contax cameras he might be willing to do this fix, since it must be fairly easy for someone who had the basic tools and experience with camera repair. Eric was kind enough to say he’d do it, and his quoted fee was ridiculously low: $20!

Other than the mirror problem, the RX seemed pristine, and I hated to part with it, so even though the eBay seller was willing to refund my money due to the obvious problem, I decided to keep the camera. I also decided the obvious, safe thing to do was to send the camera to Eric, an experienced professional with reasonable fees and fast turn-around. Of course, within hours my impatience was getting the better of me, and I began wondering if this repair might be something I could manage on my own. I soon decided to go ahead and give it a shot. Hopefully I won’t regret it. I dug around the internets for a long time, and didn’t find a whole lot of info on this repair. One guy has a YouTube video where he demonstrates the simplest possible fix — heating up the mirror and carrier with a hair dryer until the adhesive softens, and then pushing the mirror back in place. He also states that after he did this repair, his mirror began slipping again later. I found a few mentions of people removing the mirror and re-taping or resealing it in place, but they were short on details, and no images of the steps. But I forged ahead anyway, figuring I’d try the quick fix first, then undertake the full remove/clean/replace procedure if that didn’t seem to be a permanent solution. So I got a few basic tools together and got started. This was all sort of impromptu and unfortunately I didn’t have a digital camera handy, so I don’t have any images of the process. Hopefully some before and after pics and a good description will be sufficient to help someone else who tries this. My legal department has asked me to state that I am not responsible for you fucking up your camera if try this at home. So there it is. :)

I got out the hair dryer and heated up the mirror carrier from underneath. The camera was on, in Bulb Mode, with my finger held on the shutter button to keep the mirror up…I don’t even know off the top of my head if I could have locked it up on this camera, but maybe that’s possible. I held the hair dryer a few inches away for about a minute or so, then turned it off and pushed the mirror upward in its carrier to see if the adhesive had softened. It moved, with not too much pressure. I pushed it upward maybe an eighth of an inch, and when I let off the pressure, it crept back just a little. This worried me, so on the spot I decided I was just going to take the mirror all the way out. I heated it some more…another minute, with the dryer on high, only three inches away. After that, the adhesive was very soft. I grabbed the mirror between thumb and forefinger (I’m wearing latex gloves for this whole operation) and tried to pull it out toward me. Not happening…I felt that to pull it out I would have to use too much force on the carrier. I tried to insert a guitar pick between the mirror and carrier. Too thick. So I grabbed a scalpel with a fresh blade and stuck it between the mirror and carrier, right where I could see the adhesive tape residue. I used the tip of the scalpel to slice through the adhesive little by little, at both adhesive points. The scalpel blade wasn’t long enough to extend all the way to the opposite edge of the mirror, but when I gone as far as I could, I gave it a gentle twist, and the mirror came away from the carrier. At this point it was still loosely stuck in there by the back edges of the tape, but I was able to free it without pulling very hard.

So now I had the mirror out. The adhesive was thick and gunky, and all over the back of the mirror as well as the mirror carrier plate. I set the mirror down on a PEC pad, adhesive side up, and carefully scraped off the residue, then cleaned it thoroughly with a PEC pad and some isopropanol. I understand that the reflective coating on these mirrors is pretty fragile, and can be damaged by most cleaners. I had read that methanol was OK, but I didn’t have methanol. So I used the isopropanol, but this was only on the back of the mirror. As near as I could tell, the front and back of the mirror are identical, and the alcohol didn’t seem to damage the reflective surface on the back. Still, the front was pretty clean, and I wasn’t going to chance it. I left the front of the mirror alone for the most part, but I did wrap a dry PEC pad around a Q-tip and buffed the front just a little. Now I had a clean mirror, ready to go back in the camera, but two problems. First, I wasn’t sure what the best way would be to reattach it. Some people had mentioned using more double-stick tape, but I couldn’t find any specific product references, and I don’t really have a good idea how strong the adhesive needs to be. I also read about someone who claimed to have used silicone sealant, and then shot with the camera for years afterward with no issues. Silicone was sounding pretty good, especially in light of my second problem.

The second problem was the adhesive tape residue in the camera, in two gunky strips across the mirror carrier. I think the right way to do this repair would have been to clean that gunk off thoroughly, and reattach the mirror with some (undetermined) double-stick tape which was the same thickness as the original. Of course, that’s not what I did. I’m sure I could have cleaned that gunk off the carrier, but it would have taken a lot of time and patience to get it all off without applying frequent force from various directions to the carrier. For someone who was mechanically inclined and had access to the right tools and no fear of disassembly/reassembly of tiny parts, it would probably be faster to just remove the mirror box entirely, but that’s well outside my range of abilities. I reasoned that if I left the residue there, it would provide the same approximate spacing that had existed between the mirror and carrier. I could apply a very thin layer of silicone around the strips of residue, and press the clean mirror down against the carrier. If I used just enough to allow a seal to be formed, and not enough to squeeze out the sides, the spacing in that gap would be maintained by the original sealant, most of which had remained on the carrier rather than the mirror. Sounds good, eh?

I didn’t have any plain clear silicone sealant on hand, so of course I went to the hardware store and bought some grabbed whatever I could find. What I ended up using was a tube of window and door sealant from Ace Hardware which was labeled “Siliconized Acrylic Caulk.” It was also labeled “clear,” but when I squeezed some out of the tube, it was white. The instructions reveal that it dries clear. It’s what I had, so I used it. I saturated the end of a Q-tip with the sealant, and applied a very thin layer the mirror carrier, avoiding the holes, but not necessarily avoiding the old adhesive still stuck to it. There’s a square cutout in the center of the carrier plate, and when the mirror goes up there’s a little “sub-carrier” that holds another tiny mirror, fitting snugly into the cutout. I assume that tiny mirror has something to do with metering, but honestly, I know an embarrassingly small amount about how these cameras work. But I avoided getting the sealant too close to that hole or any of the small round cutouts in the plate. Again, I regret that I don’t have a photo, but here’s an illustration of what the carrier looked like. Gray represents the metal of the carrier, white represents the cutouts, black represents the old adhesive, and light gray is roughly where I spread the new sealant. I would emphazise that I used as little as possible; I think it would be bad if the sealant leaked out at the sides of the mirror, and worse if it pressed out into the cutout areas, getting on other parts.

Once I had applied the sealant it was time to re-insert the mirror into its carrier. Not much too this part…I just held the edge of the mirror with gloved fingers and carefully stuck it back where it belonged. I then pressed it down firmly in the center and at all four corners. That’s it. All done. I suppose it probably isn’t great to be pressing the mirror down onto the carrier, and that these precision parts are somewhat fragile and have small tolerances for operation. However, there wasn’t much else I could do without having the mirror box entirely removed, and I also reasoned that if these mechanisms are engineered to undergo a hundred thousand shutter clicks or more without failure, I’d probably be OK. The mirror isn’t totally opaque, and when I peered into the box with  flashlight, I could see milky white splotches where the fresh sealant was. I set the camera down on its back, no lens attached, no body cap, and allowed it to cure overnight. In the morning, I couldn’t see the white splotches anymore, so it looked like the stuff had dried and the camera was ready for a test run.

In addition to not breaking or damaging sensitive internal parts of the camera, this repair needed to accomplish two things. First, to reposition and reattach the mirror securely, and second, to leave the mirror surface roughly the same distance from the plate as it was when the camera was new. I don’t have any idea what the margin for error is here, but if the mirror was sitting too high, it could cause misfocus. I have no way to measure this, but just by eye, it looked about the same. I was also still able to insert the tip of the scalpel between mirror and carrier, and I was still unable to do this with the same fairly thin guitar pick I had tried before. So I’m hoping I’m in the ballpark. The true test would be to shoot and see what happened, so this morning I shot a quick roll. I took shots wide open as well as stopped down to f/11. I took shots where my subject was near the minimum focus distance, and shots where I focused at infinity. As I focused carefully, I tried to assess whether using my own eyes (with the matte screen and/or the split prism) matched up with the camera’s electronic focus confirmation, and in all cases it seemed to. Finally, I’m happy to report that focus was right where I expected it to be in every frame of my 36-exposure test roll, and the lens is razor sharp and beautifully contrasty. I’m calling this a success. The one remaining variable is whether the sealant will do its job over the long term. I just finished a second roll (not yet developed), and checked the mirror position, and it’s still flush with the carrier, so everything looks great for now!

I’ll post some results from the first roll or two soon, but for now I have a couple more pics to add related to the mirror issue. First, a closeup of the repaired mirror, showing that the front edge is flush with the edge of the carrier:

Finally, before and after pics of the camera with the mirror in the down position, showing the difference in spacing between the front/bottom edge of the mirror and the mirror box. Now that I know where stuff is supposed to be, I think I could easily identify a camera that exhibited this issue without even raising the mirror.

Leave a Comment

{ 9 comments… read them below or add one }

jeff cooper April 18, 2012 at 10:16 pm

Great job with the repair. Nice looking body!

Reply

Todd April 18, 2012 at 11:16 pm

Man, you are going to have to shoot a little bit with this thing. The complete absence of mirror slap is hard to believe.

Reply

Bogdan May 11, 2012 at 6:47 am

Hello, Todd! Thanks a lot for the article, it helped me to solve a problem with mirror. But apparently I did something wrong, and now I have little difference in focusing with the screen and the DFI. What can you advise about correcting mirror position / focusing adjusment?

Reply

Todd May 11, 2012 at 8:28 am

Hi Bogdan, sorry to hear your screen is out of adjustment! I presume you’ve gathered that I am not a professional camera repair guy. I knew I was taking a chance when I did this, and the biggest risk was perhaps that the focus would be off, and that my window caulk would be a fairly permanent step that I could not undo.

Hopefully you didn’t do what I did, but rather, used tape, in which case you can reheat to soften the adhesive, and try again. I can’t say for sure what your issue is but most likely it’s simply that the mirror is no longer flat in the carrier, or that its height relative to the carrier has changed. For example, if your adhesive solution was too thick, and you raised the mirror, or if you thoroughly cleaned the carrier (which I did not) and your adhesive solution is too thin.

The more ominous possibility is that you somehow altered the position of the carrier itself, but hopefully that’s not the case.

I know this probably wasn’t extremely helpful, but it’s all I have. :(

Please let me know if you do find a solution!

Reply

Bogdan May 12, 2012 at 4:25 am

Todd, thank you for your understanding and compassion! I understand that you are not a professional camera repair guy, and all the responsibility lies on me certainly ;) I’ll try to experiment with tape, and tell you what I get.

Thank you again!

Bogdan July 16, 2012 at 4:56 am

Hi, Todd.
I’m sorry, I forgot to write you about the solution, actully there’s no solution ,) Apparently silicone adhesive decreased (or increased) in the volume over time and now everything works perfectly.

Many thanks again to you!

Reply

Todd July 16, 2012 at 9:30 am

I was just wondering about this a couple of weeks ago. That’s great news, and thanks for getting back with your reply! This is such an incredible camera, and it’s good to hear there will be one more in service.

Reply

Jerry Harwood December 6, 2012 at 10:34 am

I have had the identical problem with an immaculate RX. My problem was slightly different; my wife bought me a C/Y lens an 80-205mm F4.5. The camera worked perfectly in all respects, UNTIL I bought an Zeiss fifty mm F1.7MM. a proper Zeiss. When I mounted the lens on the RX, the shutter fired normally, but the mirror stayed UP! Took the lens off, the mirror came down !
I thought that perhaps the lens was faulty, and sent it back to the dealer. I did this because as the C/Y lens operated correctly, I assumed the new lens was faulty ! Wrong ….. So now the dealer is as puzzled as I was. So we are at the stage that I sent the RX back for checking as well. Where it is now.
I had the camera serviced, to help things along. Now I wait .

Reply

Todd December 6, 2012 at 2:30 pm

Hi Jerry, it’s not clear to me at all what’s going on there, but if you find out, I’d love to know!

I’d also be curious to who’s working on Contax stuff for you, since I had a hard time finding anyone willing to do the work.

Reply

Previous post:

Next post: