The optional 645 Pro AE Prism Finder with Mamiya's exclusive A/S Matrix Metering System offers spot, average or matrix measurement in manual mode or aperture priority auto. Electronically timed shutter speed accuracy in 1/6 step in auto mode, and +/- 1/3 step exposure compensation for fast and precise bracketing. With Mamiya's leaf shutter lenses linked through the Power Drive Grip II, the A/S Matrix Meter reads out the correct shutter speed required for perfect fill flash exposure. This aperture-priority AE finder offers both spot and average metering choices, as well as its own special auto-selection (A/S) function that switches between spot and averaged automatically to suit the shooting conditions. Provision to accept diopter correction lenses and Variable Diopter Flip-up Magnifier. For 645 Pro.