Tamron and Sigma have both announced updates for their lenses to provide full compatibility with Canon's EOS 5DS and 5DS R models. Both firmware updates refer to behavior in live view shooting, something that has also caused problems in the Canon EOS Rebel T6s and T6i. This suggests that Canon's latest models feature a change in the way they drive lenses.

Tamron's release states that for six of its lens models, autofocus doesn't work with the 5DS/5DS R in live view. With Sigma's lenses, the cameras do not operate at all in Live View mode. Both manufacturers state that lenses shipped after May 11, 2015 are not affected by the issue.

As this issue was previously addressed in the T6s and T6i, firmware for lenses is already available. Owners of affected Tamron and Sigma lenses are advised to get in touch with their local authorized service center.