Firmware Version 1.1.2 incorporates the following enhancements:
1. Increases the manual focus speed when the manual focus speed switch is set to 1 or 2.
The speed when the switch is set to 3 (slowest speed) will be unchanged.
2. Improves the image stabilization effect during handheld shooting with a slow shutter speed when used with EOS 5D Mark IV, EOS 6D, or EOS R.
Note:
This firmware update adds a full time full time manual function and only applies when combined with the EOS 1DX MK II during One Shot AF only. To enable full-time manual focus function during Servo AF when used with the EOS-1D X Mark II, the lens must be sent to a Canon Service Center.
If the lens’ firmware is already Version 1.1.2, it is not necessary to update the firmware.
The lens’ firmware version can be checked from the camera’s menu.
Firmware download links:
https://www.canon.com.au/camera-lenses/ef-400mm-f2-8l-is-iii-usm/support?option=drivers
https://www.canon.com.au/camera-lenses/ef-600mm-f4l-is-iii-usm/support?option=drivers
Contact Information for Inquiries
Canon Australia: (02) 8873 8585 or email cameraservice@canon.com.au
Canon New Zealand: 0800 222 666 or email helpdesk@canon.co.nz