Actually it is something like 8 x 4 = 40 mm, because you can get maximum 3x in 7D's 5X mode, most if not all CF cards today cannot reach 3x continuously, but by a smaller aspect, you can get something like 2k, 5184 / 2000 = 2.592, 2.592 x 1.6 = 4.147, and 4.2 x 8 = 33.2 mm
But, 8mm is a fisheye, the widest non-fisheye is the 14mm full-frame lense, which I heard from rumor.