Hey Paul,

I don't mind telling you - I haven't got a clue!
Have you posted this on the Canon forum? One of the Canon guru's may have an answer. The only other thing I can think of is call Canon tech support.

I do agree that manual focus with a DSLR does indeed seem to be more difficult than it is with a manual focus film camera. Again, I don't have a clue as to why, I only know that it is harder.