From Sigma:
Thank you for purchasing and using our products.
We would like to announce the update in the lens firmware of the SIGMA 20mm F1.4 DG HSM | Art Canon and SIGMA 24-35mm F2 DG HSM | Art Canon on the SIGMA Optimization Pro.
The latest firmware update makes it fully functional with the Canon Digital Cinema Camera EOS C300 Mark II.
For those customers who own the following products, please update the firmware of the lens via the SIGMA Optimization Pro.
[Applicable products]
SIGMA 20mm F1.4 DG HSM | Art– Canon mount
SIGMA 24-35mm F2 DG HSM | Art– Canon mount
[Benefit of this firmware update]
Please be sure to update SIGMA Optimization Pro to the latest version before upgrading the lens's firmware.
You can download the latest version of the software from the following page:
http://www.sigma-global.com/download/
We appreciate your consistent support for our company and products.
B&H carries the Sigma USB Dock.