What lenses are you having problems with please?
Some of my old Sigma's won't auto focus on my 30D or 7D although they are fine on the 35mm EOS 3 and a very old EOS D60.
What lenses are you having problems with please?
Some of my old Sigma's won't auto focus on my 30D or 7D although they are fine on the 35mm EOS 3 and a very old EOS D60.
Those lenses were designed for the film cameras, and will work on some digital bodies but not others. They use the same EF mount, but the electronics are a bit different. Sort of awkward given the aperture and auto-focus systems are both run by electronic motors within the lenses!
My lenses are a 120-300, 150 macro, 18-125 all Sigma and a 500 Canon. I used to have a 135-400 sigma that had to be chipped. As I was the original owner, Sigma did it for a fiver.
Sigma offer a "chipping" service for some of their older lenses that become incompatible. Might be worth checking if they do it for your lenses rhody, though it sounds like yours might be particularly old if they don't even work on the 30D