« Previous page X2-PRO system for DSLR : X-811 : X-811 X2-mount for Canon 1Dseries This X-811 is needed to mount any Canon 1D-series SLR to the X2-PRO system. (1D,1Ds, Mk 1,2) The X-811 places the CCD exactly in the optical center of the lens, in horizontal as well as vertical position.