The MSX uses the basic 42mm mount, but the MSX lens have an additional coupling that allows the MSX body to meter wide open with the MSX bodies, or stop down with any other camera and the MSX bodies will work in stop metering with any 42mm lens. The other 1000 and 500 are basic bodies, meters in stop down mode. Some models have both spot and center average metering. The Mamiya lens are very sharp. If the meter is working it is a good basic body for 42mm lens.