To the Users of the EF300mm f/2.8L IS II USM, EF400mm f/2.8L IS II USM, EF500mm f/4L IS II USM, and EF600mm f/4L IS II USM Interchangeable Lenses for Canon Digital SLR Cameras

Please see the changes to the “Identification Procedure” section below regarding the criteria for affected serial numbers. The identification procedure has been enhanced to include the first, second and third digits from the left in order to more precisely identify affected products.

Thank you for using Canon products.

Firmware Version 1.1.1 is for lenses with Firmware Version 1.0.0. If the lens’ firmware is already Version 1.1.1, it is not necessary to update the firmware.

Canon has released a firmware update for EF300mm f/2.8L IS II USM, EF400mm F2.8L IS II USM, EF500mm f/4L IS II USM and EF600mm f/4L IS II USM lenses. This firmware update will be performed by Canon Service Centers. Please contact us using the contact information listed at the bottom of this page.

Firmware changes:
Firmware Version 1.1.1 incorporates the following enhancement:

1. Changes the control algorithm of the focus drive, and enhances the drive’s responsiveness for more precise focus and adjustments. In particular, the new firmware enhances the AI servo AF capability of the lenses to track objects that move irregularly in sports events, such as soccer or rugby.

The first, second, third and fourth digits from the left in the serial number (10 digits) for lenses equipped with Firmware Version 1.0.0 are as follows:

Lenses with serial numbers other than those listed above are equipped with Firmware Version 1.1.1 or later.