For full aperture control, the non-reversible modification to cut off at least 3mm off the aperture lever tip at rear of lens is required. The allowable length is 9mm from face of lens mount.
This is to clear the camera mirror box or else the lens will only shoot at widest aperture. This modification will not impact its use with its original mount and camera.
1. Align mounting mark on CY lens with oblong mark (О) on mount ring.
2. Turn the lens clockwise to mount.
3. Turn the lens anti-clockwise to separate from camera.