Firmware version 1.3.0 for the EOS-1D X Mark III incorporates the following enhancements:
1. Enables 2nd curtain shooting sync during radio transmission wireless flash shooting when the Speedlite 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 Speedlite 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.
Click the following link to download the firmware update: