I think Canon is using XL mount - that may be different from your 1/3"...

Does anybody on this thread know whether Canon XL lens mount is compatible with JVC 1/3" mount?

I've read somewhere that one can interchangeably use Canon and Fujinon lenses, but don't remember the details... Anybody could chime in and clarify?

I just now looked at a Canon XL-H1. It is not the same mount as the JVC ProHD cameras use.

No, indeed, the mount is anything but the same. The JVC should be a standarised mount (just smaller then the usual 1/2 inch or 2/3 inch). The Canon's prop. (and it includes support for canon lenses as they are completely different: they don't have the grip on the lens, but on the camcorder)