Contax RX not displaying the right aperture

Todd Adamson

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I just took delivery of a Contax RX with a Vario-Sonnar 28-85/3.3-4 lens. Both camera and lens look brilliant, like new, but I think I either have a problem, or am perhaps missing something. The aperture is displayed in the VF, but it isn't the right aperture. With the aperture ring wide open at 3.3, the display reads 2.8. With the lens stopped down fully, it reads 19. This is true in both Av and M modes.

The manual says the aperture is only displayed in half-stop values, and specifies that with a 3.3 lens it will read 3.5. The aperture ring seems to have very solid, defined clicks. At 3.3, display reads 2.8, but I can actually turn the ring just a bit clockwise from there, and the display goes to 2.4. It doesn't click in this position, and if I let go, it goes back to 2.8. There's a click between 3.3 and 5.6 on the ring, and there the display reads 3.5. At 5.6 on the aperture ring, the display reads 4.5.

Am I missing some sort of "calibration" step? When manually-operated by the tang on the lens mount, the aperture seems very snappy, no indication of any problem. I've unmounted and remounted the lens carefully a few times.

Thanks for any help!
 

TheFlyingCamera

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Sounds like SOMETHING is out of alignment - either the pick-up tab on the body or the aperture indicator tab on the lens. I'd try one of two things- make sure when you mount the lens on the body that the aperture is set to minimum. If it doesn't show the correct value at that time, then I'd try getting my hands on a different C/Y lens in MM mount, preferably a fixed focal-length lens (just to eliminate a variable). If that lens shows correct aperture on the body, then you know the problem is with your lens mount (it could be that someone repaired your lens in the past and positioned the MM aperture-indicator tab in the wrong place). If not, then it's probably the body that is at fault. Either way, one piece or the other may be needing a trip to the repair shop. If you have a warranty on the purchase, I'd evaluate this quickly so you can turn this around and get it covered under warranty or replaced/refunded. They're both amazing tools, and you'll love your results. Best of luck with it!
 
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Todd Adamson

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Thanks a lot for the reply. The lens repair theory was one I had kicked around. I don't know of anyone else around here that would have a Contax system, unfortunately. I just bought it on eBay. Seller seems great, and the gear is pristine. I'm sure they'd take it back for a refund, but I got a good price (I think), and I think I'd have trouble finding another body this nice. If I could manage to confirm that the lens is the problem, I'd send it back and pick up a 50, or a 28/2.8.

Heading down to my local shop now. I doubt they'll have anything Contax, but the owner's quite knowledgeable, so he may be able to determine what the issue is.
 
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Todd Adamson

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BTW, I just took your advice and remounted the lens making sure it was at min aperture. Didn't change anything.

Any idea how difficult it is to disassemble and reposition the tab on that lens? I'm fairly competent mechanically, but have no experience working on lenses.
 

TheFlyingCamera

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Disasembly and re-positioning of the tab can PROBABLY be done (haven't done it myself) with just removing the screws that hold the rear lens mount plate in place. I don't know if the MM tab is part of the barrel or if it is separate. I wish I still had my RX and lenses to look at and give you more advice.
 

Jeff L

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It was a long time ago, but I had a few CY lenses that read a tad out. I changed some mounts- cheap and easy to do at the time.
I wouldn't worry too much about it being a 1/2 stop or so out. It didn't seem to affect my exposures at all.
I have this lens at it is very very good, but does flare at times. I found it to have the least flare with no filter at all (makes sense) but I keep a filter on it to be safe. I found the Hoya multicoated flared the least.
Good luck
 
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Richard S. (rich815)

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Mine RX has done this for years. I guess the tab on the body is 1/2 stop out in terms of display but not actual aperture as far as I can tell. Awesome camera. If you got a good deal, all else is fine and it does not bother you then ignore it.
 
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Todd Adamson

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Thank you everyone for the replies. I just shot a roll and will develop tonight. If everything looks good and continues to look good with my exposures, I'm actually inclined to just let it slide. I gotta say, this camera feels so good to shoot with, I almost don't care if the resulting frames are horrible. LOL.
 

Richard S. (rich815)

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Yeah, the RX has a wonderful feel to it. The mirror-slap is one of the softest out there amongst SLR's I think.
 

TheFlyingCamera

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You can almost do street photography with it were it not for the big black blob in front of your face, made all the more obtrusive by that giant 28-85 lens stuck to the front of it! But yes, it does make a good stealth camera from a noise perspective. I loved mine, but eventually I got tired of the bulk of the system and traded it all in toward a G2 outfit.
 
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Todd Adamson

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Sadly, the new RX is messed up.

I just developed my roll, and every frame looks like the sample below. The seller is willing to take it back. He also has an ST, and I went back and forth before buying this on which body to get, so maybe I'd be willing to trade for the ST. Not sure what to do. If I knew exactly what the problem was, and the probable cost to fix it, I'd be better able to make a decision, but that's probably to much to hope for. Anyway, though I would post this here and see if anyone had any good ideas about how bad this problem is. Not sure if it's a problem with the mirror, or shutter timing, or what? I do know these cameras had occasional problems with the mirror sliding out of its glue, but this wouldn't be that, would it?? I assumed that mirror slide problem would be more catastrophic.

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Todd Adamson

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OK, here's something else that might provide a clue as to what's wrong. I didn't notice it immediately, but every image seems to have ghosting. Here's a crop of maybe a quarter of one frame where it shows up very clearly:

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Todd Adamson

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Umm...haha...hooOoly crap. I just put the camera in bulb mode, with no lens on, to see where the mirror went when it was up. SUcker's sticking out about a quarter of an inch. I can't believe it's not hitting the lens bayonet!!

SHould I try to fix this? The camera is just amazingly sweet otherwise.
 
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Todd Adamson

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OK, I'm being dense. Of course the mirror is hitting the lens! It's hitting it on the way up and therefore stopping most of the frame from ever being exposed. Duh. Really surprised it hasn't broken. Anyone know of a repair shop that will do this for a definite fee? Trying to decide between returning an otherwise beautiful camera, or having it repaired professionally, or attempting to do it on my own. Any advice will be appreciated. Here are some pics of the mirror. Don't laugh.

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Richard S. (rich815)

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Mirror slipped. Needs to be reglued. A chink in the armor of these babies but not a hard fix for a technician.
 
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Todd Adamson

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Anyone have a technician or shop they would confidently recommend? I did email Eric Hendrickson, who seems to work only on Pentax gear. But I tried him just in case, because he gets a lot of accolades, and I figure this is probably an easy fix for anyone with a lot of experience, even it's not Contax-specific experience.
 

Richard S. (rich815)

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Todd Adamson said:
Well, I'm impatient, so I did the repair myself. First roll today looks great! Hope the repair holds up...
Click to expand...

Nice shot.

What exactly did you do to repair it? My RX mirror had slipped slightly a year or so ago. I used a hair dryer on low to warm the mirror slightly to soften the adhesive and carefully applied some mild upward pressure to slide it back into place, then took it outside where it cooled down fast (it was about 45F that day). It has stayed since but I imagine might slip again. Thought of prying it off and super-gluing it more permanently but have been too shy. How did you do it and what did you use?
 
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Todd Adamson

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I tried the pushing it back into place thing, but I could watch it rebound a little bit, so I kept going until the adhesive was soft enough to remove the mirror. Then I cleaned the mirror and reglued it with some window caulk. LOL, I am impatient, and that's all I could find. I'm going to make a blog post about the repair later today (I hope), and when I do, I'll come back and link it for anyone interested.
 

Richard S. (rich815)

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Please do! My first thought is to worry that window caulk would be too thick and perhaps have the mirror not in sync for focus but your image example belies that! I was thinking an epoxy myself. I guess I muster up more courage and warm the mirror again and work it back and forth to remove it, them glue it down. Watching for your blog post link.....
 

Richard S. (rich815)

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