I have a 7d mkii camera and I bought said lens. Problem is it won't work and comes up with err 01. Clean contacts on lens. I have done so but still not working. Any advice would be appreciated. Thanks.
I'm not sure how old of a copy of the lens you have but seems that sigma ended up re-chipping the lens earlier in the EF mount days. https://www.dpreview.com/forums/thread/579152 you can see this thread is 20 years old. May be worth a call to sigma if your other lenses work fine and you are unable to get past the error with cleaning contacts on both lens and body as would be the normal 1st step.