From Canon:
Firmware Version 1.0.5.1.00 for EOS C500 incorporates the following improvements and fixes.
For EOS C500
For EOS C500 PL
Support
Download Firmware Version 1.0.5.1.00 for the EOS C500 / C500 PL.
Firmware Version 1.0.4.1.00 for the EOS C100 incorporates the following improvements and fixes.
Note: Firmware Version 1.0.4.1.00 is only for EOS C100 cameras without the Dual Pixel CMOS AF Feature Upgrade. If the EOS C100 camera has had the DAF Feature Upgrade applied, please download Firmware Version 2.0.4.1.00.
Support
Download the new version of the Instruction Manual for the EOS C100 which provides more information on the new features and benefits available in this firmware update.
Download Firmware Version 1.0.4.1.00 for the EOS C100.
Firmware Version 2.0.4.1.00 for the EOS C100 incorporates the following improvements and fixes.
Note: Firmware Version 2.0.4.1.00 is only for EOS C100 cameras with the Dual Pixel CMOS AF Feature Upgrade applied. If the EOS C100 camera does not have DAF Feature Upgrade applied, please download Firmware Version 1.0.4.1.00.
Support
Download the new version of the Instruction Manual for the EOS C100 which provides more information on the new features and benefits available in this firmware update.
Download Firmware Version 2.0.4.1.00 for the EOS C100.
B&H carries the Canon EOS C100 and C500 Cinema Cameras.