Today the guys over at Canon Rumors confirmed an issue that may affect the Canon EOS-1DX and Canon EOS-1DC, Canon's flagship DSLR bodies. Turns out they might not auto focus in the cold. This issue first started popping up in the forums nearly a year ago (April 20, 2013) and have largely been unconfirmed until now. While there is still no official word from Canon or CPS an "anonymous source" contacted Canon Rumors with a fairly through explanation, diagnosis, and repair statement that looks like it might be an internal memo at CPS.
Camera “does not autofocus”, “does not search in AF”, or “does not focus in AF search” depending on the reporter or the camera settings; specifically, the focus cannot be achieved in low temperatures (under 0 degree Celsius).
* Although there has been no reported occurrence on the EOS-1D C, the mechanical structure of the Mirror Box Ass’y is the same as the EOS-1DX, so the EOS-1D C is included in the affected product.
This phenomenon is due to the Locking Claw of the Sub Mirror (mirror for AF) going over the Locking Pin. The Sub Mirror’s angle becomes deviated and the light rays for AF does not fall on the AF sensors, causing the “does not autofocus” phenomenon.
Service of Affected Product:
To control the torque, the process to check the Locking Claw’s going over torque of Locking Pin has been newly incorporated. (From production on January 24)
Handling of units in question: If the user complains about this specific phenomenon (does not autofocus in low temperature), replace the Mirror Box Ass’y with the ones to be shipped in the future (CY3-1661-010 or CY3-1687-010).
Handling of general repairs: If the user does not mention this phenomenon, please handle as normal repair.
Of course, the Canon EOS-1DX / C are Canon's flagship cameras, specifically designed to work in all situations and weather conditions, a lack of performance in the cold could be a serious deal breaker to wildlife photographers or people living in cold climates. On the other hand, photographers living in warmer areas might never experience this issue or know if their camera is affected. It will be interesting to see Canon's handling of this situation over the next several weeks.
Below is an image by Canon Rumors comparing the mirror locking claw of a normal 1DX and a defective model.
[Via Canon Rumors]