This'll be the last 10D blog entry for a while. I've spent the last couple of days trying to speak to someone in Canon who could a definitive answer on whether my double-zero problem was indicative of a lens fault, a camera fault or some incompatible. Everyone I spoke was polite and tried to be helpful, but I guess they don't have the folks who know the guts of this stuff answering the phone. The last person I spoke to said just send the lens, but I had submitted a problem description through the Canon Self-Service pages. I received an e-mail back from them saying send camera and lens. So I figure (a) my symptoms were probably considered by someone with better understanding than telephone agents, (b) sending both items is the sensible strategy and (c) I can ask for the 10D to be recalibrated at the same time.