i recently bought a 7d, fantastic camera. minus the sensor, totally comparable to the 5d mII
my tamron 16-50 f2.8 works great with it. but my 50mm f1.8 and kit lens from my old, ok get this... 300d! do not.
However they both work fin on my friend's cameras, work fine on the 300d, 5d, 60d and 600d(we love our canons)
what happens is the body dose not see the lens. i cant change the aperture, the camera displays "00" as if there wasn't a lens installed ;(
Not only that but auto focus dose not work. the lens is getting power, the focus ring resists movement...
The 7d works fine with my buddies Canon EF 24-70mm F2.8 L USM Lens, My tamron 16-50 f2.8 and my canon f4.5 55-200. I just did a firmware upgrade from 1.2.3 to 1.2.5 hoping that it would fix the problem but it didn't.