EOS 5D Mark III Firmware Version 1.2.3
Firmware Version 1.2.3 incorporates the following improvements and fixes.
Fixes a phenomenon in which the flash may not fire depending on the timing of when the shutter button is pressed.
Fixes a phenomenon in which the AF microadjustment value may change.*
Fixes a phenomenon in which the LCD monitor may show a line of false color along boundaries of high contrast.
Fixes a phenomenon in which the histogram of a LiveView image is incorrectly displayed when an HDMI cable is connected.
Enables the brightness of the camera’s LCD monitor to be adjusted even when an HDMI cable is connected.
* The phenomenon listed in 2 was addressed with Firmware Version 1.2.1, and has been further improved with Firmware Version 1.2.3.
http://www.canonrumors.com/2013/10/eos-5d-mark-iii-firmware-1-2-3-available/
