Adjust Back-focusing issue on a Contax G1

Hi.

My Contax G1 is having back-fucus issues, and I would like to know if it's possible to correct the passive AF the same way a G2 is able to do?
When the camera is set up on a fixed distance, the AF measures a longer distance than it actually is - which then leads to back focusing (ears are in focus when I want the eyes to be in focus).
I don't have the repair manual for G1, and would like to check here if someone have experience with this.
According to the G2 repair manual, it should be possible to adjust the measured AF distance for 0.5m, 1.0m, 2.0m and 2.95m. However, I can't fint the correct item no. in Manual Adjusting Mode.
It should be 1A for the G2, but there's no 1A option on the G1.
Does anyone here know what to do, or have the G1 repair manual available?

Which lens are you having this problem with? My G1 never had any difficulty w/ the 50 lens, but the 90 was a different story. I had to practice w/ it by pointing it at different things and seeing exactly where the camera thought the focus point was.

You can manually focus the lens too, but I think it involved going into the menu so I never did that. Lots of people have had focus issues w/ the G1 cameras, but in my case it was just understanding how it worked best w/ that 90 Sonnar.

They're also known to have focus issues if there isn't good connectivity between the camera's lens mount and the lens. See if you have any bluish stuff there. If so, clean everything well, and make sure the batteries are full voltage and the contacts are clean.

momus said:

Which lens are you having this problem with? My G1 never had any difficulty w/ the 50 lens, but the 90 was a different story. I had to practice w/ it by pointing it at different things and seeing exactly where the camera thought the focus point was.

You can manually focus the lens too, but I think it involved going into the menu so I never did that. Lots of people have had focus issues w/ the G1 cameras, but in my case it was just understanding how it worked best w/ that 90 Sonnar.

They're also known to have focus issues if there isn't good connectivity between the camera's lens mount and the lens. See if you have any bluish stuff there. If so, clean everything well, and make sure the batteries are full voltage and the contacts are clean.

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Thanks for the reply!

The back focus problem is most visible with the 45mm wide open (f 2 and 2.8). The 28mm when stopped down isn't much of a problem, however, the back focusing issue is visible when shot at f2.8 close up. All connections are clean and I haven't had any problem with focusing in general, since I'm used to handling this type of single focus point AF (focus and recompose).

I did a focus test where the camera was mounted on a tripod facing a wall with focus chart (vertical line). When set up at 1.00 m from the distance-reference index, the AF showed 1.05 m. At the 2.00 m distance the AF showed 2.20 m, and likewise 3.30 m when camera was set up at 3.00 m. To check if the AF distance is correct I shot a frame on all the above distances, and additionally with manual focus where MF was set at the exact same as the distance to the focus chart (MF at 2.00 m at the 2.00 m distance). When viewing the scans, the ones shot with AF clearly is somewhat out of focus and the MF frames are in focus. All frames were shot at f 2.0.

This test got me searching the web for possible answers, and I came across some info regarding calibrating passive AF on a G2.
So my question is still if it's possible to calibrate the G1 like with the G2.

In the meantime I'll do some more test rolls and find a way to compensate the back focus (like moving a bit back after locking focus).

Hi, have you managed to find a solution? I am facing similar problem with the G45.