What those other guys said. There is nothing special about the MX. The flow is essentially the same as for stop-down metering on a Spotmatic and K-mount bodies except that you have to manually stop down the lens using the A/M switch. It goes like this:
- Choose your desired shutter speed
- With the lens stopped down (A/M switch in M position), meter the subject using the aperture ring to select the appropriate f/stop
- Move the A/M switch back to the A position
- Frame and focus
- Move the A/M switch back to the M position
- Release the shutter
- Repeat steps 3-6 until you change subjects, change shutter speeds, or the light changes
Steve