A multicoated lens to accomodate the latests M42 bodies produced by Mamiya. This ultra wide angle performs rather well in many ways: distortion is quite low, resolution remains good at the corners, and the lens is not too prone to flare. This particular lens has warm tones and saturates greens.
The SX series allow open aperture metering on Mamiya bodies only, and the pin that transmits the aperture information to the body could prevent mounting the lens on adapers, unless it is removed. Also worth mentionning is the absence of an auto/manual diaphragm switch. This again will cause problems when the lens is mounted with an adapter. Works well on spotmatics, though.