The "Big Guy" is Canon's largest EOS prime lens, a ridiculously huge 1200mm monstrosity. There are only about ten of these things in existence. Sports Illustrated owns two of them. Generally speaking you have to be a major corporation to even think about buying one, as they're individually hand milled in Japan to the tune of about USD$80,000 each.
Remember that the XL1 EOS adapter multiplies the focal length of any EOS lens by a factor of 7.2, so this 1200mm lens had an effective 35mm equivalent focal length in the neighborhood of 8640mm, which isn't a lens anymore, but a telescope.
Kevin Fogarty of Canon Professional Services reads the lower line of an optometrist's eye chart on an office wall about twenty blocks away. But seriously, you could actually see a license plate clearly on a car about a half-mile down the street. We did get the attention of some passing cops; not surprising since this rig looks like a bizarre kind of rocket launcher.
