I think I just bricked my son's Canon lens! Today he bought a used Canon EF-S 10-18 STM for his Canon T4i, and it was working perfectly.
I thought I'd compare its IQ to my EF-S 10-22 which I was using on my a6500 via Commlite adapter. (Terrible blurring in the corners, don't even try it on mirrorless — no such blurring on the Canon SLR.) So I put the 10-18 on my a6500, and it wouldn't even recognize the lens. F stop was reported as 00, and no autofocus. No manual focus either, because this lens is focus by wire.
So I thought no biggie, and put it back on his T4i. But now it won't work on the Canon either — F 00, no focus, no red focus points, and when I try to click the shutter I get an error 01, communication error with lens. I tried all the tricks. Clean contacts, remove battery, re-mount lens, no joy. So I think this lens is ruined.
Anyone else experience this? Is there a fix for it, or do I have to give him my 10-22 in compensation?
Whelp, that's enough third party lenses for me.