I have had a Sigma 150-600mm C for a shortwhile now, generally I am quite pleased with it however there are times when it is frustrating to us.
Quite often at the 600mm Zoom it struggles to focus (using with Canon EOS7DII and EOS550D) to the extent that it continually vibrates as it tries to find focus. Sometimes it will just turn focus to minimum and stop responding. Mostly this happens when focusing close to infinity and or in fair/shade light conditions.
I have also noticed that some photos taken at 600mm show 175mm in the EXIF.
Have I got a dud or are these issues common occurrence with this lens.
Should I return the lens for repair under warranty or do I have to live with these shortcomings.