Well, alot of people already have EF glass, which is why BM made their camera that way. They opened up to a HUGE market by doing so and it was very smart of them. I just have all nikon glass (started with redrock m2 35mm adapter for my hvx now im using the fs100) and whats great about using nikon glass for non-nikon cameras is that 90% of the lenses have aperture rings and the other 10% can be controlled by a non-electric control on the rear of the lens. Because of this, adapters are cheaper than canon adapters because canon you need to change the iris electronically. You can use nikon lenses on any camera and have full manual control, unlike canon lenses. But, since BM build the EF mount into their camera, it will have the full control of the lenses, which is a big plus. Tons of 7d/5d users have probably already ordered the BMC and have 10k in canon glass to use on it.