I urgently need to know how much (distance) the rear element of the lens is recessed in the lens body from the mounting flange when the lens is focused to infinity... I don't have access on the lens as to measure the distance myself... Note that as mounting flange is the part of the mount that comes in contact with the body's mount (not the part that extends and has the CPU contacts on it)... Please be as accurate as possible... Thanks in advance...