Canon EOS 3 focusing issuel - Back focus?

[Gimenosaiz]

Hello!

Here again ... with another problem. I have got a "new" EOS 3 body. The other ... died
This one seems to have a "back focusing" issue, at least with most of my EF lenses (3 of four, the 135/2 seems to be an exception, don't know why).
I've seen this with:
EF 50 f/1.4
EF 85 f/1.8 (not so bad)
EF 70-200 f/2.8 II L

In this one I try to focus the iris...
(there was a url link here which no longer exists)

Any idea?

Thanks a lot!

Cheers.
Antonio

 

[Ron789]

Do you use autofocus (eye-controlled?) or do you focus manually?

 

[Gimenosaiz]

Do you use autofocus (eye-controlled?) or do you focus manually?

Hello!

I use autofocus but I don't use the eye controlled function...
Thanks

 

[Ron789]

2 causes I could think of:
1. The iris is too dark with too little contrast for the camera to focus on, or
2. The focusing screen is not mounted correctly; take it out, check the screen and the frame for any anomalies, clean it and put it back in, making sure that it is well positioned and aligned.