Postman Loc: Florida

I have a Canon R6 with all EF mount lenses and use a Canon RF to EF adapter. My Sigma 24-105 F4 frequently causes the camera to display an error code for lack of communications with the lens. I have cleaned all the contacts on the camera, lens and adapter many times with varying degrees of success. I have restarted the camera and removed the battery again with some success. A second issue with this lens is inaccurate exposures, the EVF shows a correct exposure but the image is 2-3 stops over exposed, I can dial down the exposure which takes 1 or 2 additional shots to achieve a good image. I have 6 additional Canon EF and EF-S lenses all of which function normally, I would appreciate any thoughts you may have to help remedy this problem.

CHG_CANON Loc: the Windy City

See if Sigma has any comments. Also, see if any R6 firmware updates make a difference. Finally, recognize Canon only supports EOS equipment. The EF-RF adapters are a subtle way to shake-off some of the competition, not purposefully, but the happenstance of lack of support for non EOS equipment is the same overall result.

Postman Loc: Florida

Thanks, the camera is updated and I have searched online for similar problems with no luck yet. Perhaps I should sell the Sigma Then I nave to sell those 82 mm filters!

CHG_CANON Loc: the Windy City

If you don't have a DSLR, might be a good action in selling the lens. But, your next high-grade lens might hit that 82mm filter thread again, where the filter would be useful. The RF 28-70 is an 82mm filter, as are a few others of the widest aperture models.

Postman Loc: Florida

Thanks for your reply, my backup is an 80D with 3 EF-S lenses, I really don’t want to sell it but it’s so unpredictable I may have to look at other options.

PHRubin Loc: Nashville TN USA

I had an old Sigma 18-250 zoom on my T2i. When I updated to my 80D it worked for a week, then started having the same issue you mention. I eventually wound up getting a new Sigma 18-300 lens for my 80D (which works fine on my R7) and have sold the T2i with 18-250. I still have the 80D, a wonderful camera.

Postman Loc: Florida

I love my 80D as well, for hiking and kayaking it is light weight and functions well. I purchased the Sigma because at the time it was somewhat better than Canons 24-105 offering. Maybe a newer EF or even the RF 24-105 is in my future.

PHRubin Loc: Nashville TN USA

Good luck, whatever you decide.