Canon has updated the firmware for the EOS 5D Mark II with the specific intention of addressing the Black Dot and vertical banding problems. See the notes from Canon below regarding Firmware Version 1.0.7.
Firmware Update Version 1.0.7 improves and mitigates the following two types of image quality phenomena that occur under certain shooting conditions.
1. “Black dot” phenomenon (the right side of point light sources become black)
2. Vertical banding noise
Firmware Version 1.0.7 is for EOS 5D Mark II cameras with firmware up to version 1.0.6. If the camera’s firmware is already version 1.0.7, it is not necessary to update the firmware.
When updating to Firmware Version 1.0.7, please also update the Digital Photo Professional and Picture Style Editor software. Firmware Version 1.0.7 can be downloaded from the bottom of this page. Updates for Digital Photo Professional and Picture Style Editor can be downloaded from the following Web site.
You can download the updates and view further details and instructions from Canon here.
For the latest news and reviews on the 5D Mark II, be sure to stay tuned to Photography Bay’s Canon 5D Mark II Reviews and Resources.