Firmware Version 1.0.3 incorporates the following enhancements:
1. Adds the ability to correct focus breathing during movie recording.
2.Compatible with cameras that support focus breathing correction.
Firmware Version 1.0.3 is for lenses with firmware up to Version 1.0.2. If the lens’ firmware is already Version 1.0.3, it is not necessary to update the firmware.
Q&A Section:
Preparations for the firmware update:
In the folder you downloaded are the firmware (RF043103.afu / file size: 2,883,636 bytes) and instructions on the firmware update procedures (a PDF file in five languages: Japanese, English, French, Spanish, and Simplified Chinese). Before starting the firmware update operations, please be sure to carefully review the instructions to confirm your understanding of the firmware update procedures.
Firmware download link:
https://www.canon.com.au/camera-lenses/rf-14-35mm-f4-l-is-usm/support?option=drivers