Just before the lock-down was implemented in Georgia, I shot a roll of film with my newly acquired Contax ST, and it took a long time for the film to get processed and the scans to be made available on line (blame the postal service).
So, here we are…
The camera is pleasant to use in the field (large viewfinder, logical commands, convenient exposure memo lock (associated with Spot metering only). It’s heavy, and the Zeiss 28-85 f/3.3-4 Vario Sonnar zoom makes for a very bulky and ponderous combo (more than 1.6 kg/ 3.5 pounds with batteries and strap). You can’t carry it with the strap wrapped around the wrist for too long – you need a backpack for any photo expedition longer than 30 min.
The zoom is sharp, but it’s a one ring design (you rotate the ring to focus, and you pull or push it to zoom in and out), and of course, the front element tends to slide out under its own weight.
Some of the pictures are correctly exposed, but the majority seem over-exposed, by 0.75 EV up to 1.5 EV.
I had not noticed it when I received the camera, but the aperture information displayed in the viewfinder does not correspond to the values on the aperture ring of the lens: at full aperture, the aperture ring shows f/3.3, but the viewfinder LEDs show f/2.8; at F/8 (on the lens), the LEDs show f/4.5; at f/22, the LEDs show f/13. Roughly 1.5 EV off except at full aperture, where the two values are closer. I tried another lens (a Tamron 28mm f/2.5 with the Adaptall II ring) – same issue. When I googled it, I found out that it’s (probably) a rather common problem related to the calibration of the “aperture linkage lever” of the bayonet mount, on the camera’s side (*).
The Contax workshop manuals describe in detail the process to follow to re-calibrate the aperture linkage lever (some people call it the “feeler”) on the body’s lens mount. Unfortunately, the process is different with each model (you need to perform an obscure sequence of key presses to access the maintenance mode of the camera), I have not found a Contax ST workshop manual yet, and it apparently requires a rather expensive Contax Planar 50mm f/1.4 as a benchmark for the calibration.
Until I find a way to fix the issue, I’m simply going to use the exposure correction dial and hope of the best.
(*) I exchanged a few emails with Peter Robinson, who repairs and reconditions a few specific Contax models in the UK, and maintains the Contax139 blog (very nice guy, btw).
According to him, the aperture transmission from the lens to the body is “analog” on models like the RTS III or the RX, but encoded (I translate it by “digital”) on the 167. I suspect the ST, being a derivative of the RTS III, and the predecessor of the RX, also falls into the “analog” category. Peter posted a few workshop manuals on his Website, and the recalibration process is described in detail for each model of camera, unfortunately there are variations in the key presses from model to model, and without the workshop manual corresponding to the exact model you own, fixing the aperture transmission lever is an impossible task.
Three sources of information:
CONTAX RX Repair: Faulty Aperture Readout
Contax catalogs and manuals at www.contax139.co.uk
More about the Contax Yashica bayonet