Firmware Version 1.3.0 incorporates the following fix and enhancements:
1. Enables 2nd curtain shooting sync during radio transmission wireless flash shooting when the Speedlight EL-1 flash is attached to the camera.
2. Enables manual flash output (excluding high-speed sync and optical transmission wireless flash shooting) to be selected and set up to 1/8192 from the camera menu screen when the Speedlight EL-1 flash is attached to the camera.
3. Improves compatibility of HEIF images recorded in the camera with MIAF (Multi-Image Application Format) standards.
4. Fixes the phenomenon that may result in the occurrence of time-out under certain conditions during FTP transfer.
Firmware Version 1.3.0 is for cameras with firmware up to Version 1.2.1. If the camera's firmware is already Version 1.3.0, it is not necessary to update the firmware.
Once the EOS-1D X Mark III is updated to Firmware Version 1.3.0 (or later), it cannot be restored to a previous firmware version (Version 1.0.0 to 1.2.1).
The following Applications have been updated accordingly:
• Digital Photo Professional 4.13.20
• EOS Utility 3.13.10
• Camera Connect 2.7.20
• Digital Photo Professional Express 1.4.0
Please download the Applications as well as the latest firmware.
Q&A Section:
Preparations for the firmware update:
In the folder you downloaded are the firmware (1DX30130.FIR / file size: xxxxxx 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 link:
https://www.canon.com.au/cameras/eos-1d-x-mark-iii/support?option=drivers