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Contax RX - Aperture readout problem


New Member
Dear All,

I would be very appreciate if anybody can help me.

I've recieved my contax rx from keh.
nfortunaly, there is a problem with camera.
Note, I can't send it back for certain reasons.

Problem description:
Contax RX is able to readout aperture values starting 1.2.
When I mount lens with minimum aperture equals to 1.4 ,
camera interprets it as 1.2;
Shortly, any aperture readouts as desired aperture minus 1 stop.

Tested with:
Planar 50 - 1.4 - readout as 1.2; 2.0 - readout as 1.7 and so on...
Planar 85 - 1.4 - readout as 1.2
Sonnar 135 - 2.8 - readout as 2.0

Mechanism condition:
The element is responcible for aperture transmittion is
electronic ring with pins (located under Contax label). When changing aperture by moving aperture ring, electronic brush is moving on elecronic ring too.

Electronic brush is moved because of it has linked with plastic inner ring which moves while aperture ring moves;

So there are two potentional places:

1) The problem may cause due inproper initial state of contact brush.
But, initial state (1.2) coincides with 1st contact - so it's ok;

2) The problem may cause due backlash (luft) of inner plastic ring which moves when aperture moving; I don't know how to correct this
because rollers which limit inner plastic ring position could't be moved;

Any suggestions?


New Member
Hi there,

Sorry to reactivate this quite old post, but I've exactly the same problem with my Contax AX.

If I shift the inside aperture ring of about 1mm seems to be ok, so I think about "enlarging" the little pin of this aperture ring (inside the body) in order to fix this problem.

Have you finally found a solution with your RX ?

Same with my Rx, but it may not be a problem

I just got a near mint condition Rx, and the the only lens I have is a Panagor 24/2.5, and the Rx shows the apertures in between those on the lens. But the Rx manual states that in Av or P mode, the camera will show apertures in 1/2 steps.

Interestingly, if I move the aperture on the lens in-between the click stops, the whole aperture readings show in the viewfinder.

Frankly, it doesn't bother me in the least as long as the exposures in Av mode come out right. I'm shooting a roll of Provia right now and will know in a few days...