Originally posted on Thursday, 15th Dec 2016. Revised 2nd Dec 2019.
Changes in firmware
Firmware Version 1.0.4 is incorporated with the following correction.
• Enhances the effects of image stabilization when using the EF24-105mm F4L IS II USM with the EOS 5D Mark IV at a shutter speed between 1/100 sec. and 1/160 sec.
Firmware Version 1.0.4 is for lenses with Firmware Version 1.0.3 or earlier.
Lenses whose third digit in the serial number is “0”. (xx0xxxxxxx)
However, units with firmware version 1.0.4 or later are not affected.
If the lens’ firmware is already Version 1.0.4, it is not necessary to update the firmware. The lens firmware can be checked through the menu on the EOS 5D Mark IV.