The Mamiya Pro AE Prism Finder FE401 offers TTL aperture priority exposure control.
Key Features
A three-way metering mode system can be set for either "Spot" (reads only center of frame), "Average" (Center-Weighted), or "Auto-Shift" (switches between Average and Spot according to relative contrast in brightness between the center and surrounding area of the frame)
This prism also has +/- 3EV manual exposure compensation in 1/3 EV steps
Light metering and calculations are performed even in the manual mode, and LEDs blink to signal when the exposure setting is correct; This feature supports shutter priority shooting as well
Metering LEDs also blink to indicate low battery warning, dark slide inserted, completion of rewinding, and over and underexposure
Type
Correct-image (unreversed) eye-level prism viewfinder with built-in LED three-way metering: Average, Spot and Auto-Shift.
Metering Range
EV1 - EV19 with ISO 100 film and 80mm f/2.8 lens. This finder features auto exposure with shutter speeds of 8 seconds to 1/1000 second (at 1/6 EV stop intervals) and manual operation with shutter speeds of 4 seconds to 1/1000 second (at 1 EV stop intervals).
Metering Options
Average, Spot and Auto-Shift (automatically switches between average and spot metering according to the relative brightness between the center and surrounding area of the frame).
Exposure Compensation
+/- 3 EV manual exposure compensation in 1/3 EV steps
Metering Pattern
Average, Spot or Auto-Shift
Useable ISO
ISO 25-6400 specified by film speed dial located on film back
Display
Backlit blinking LED indicators on left side of viewfinder for shutter speeds; metering method LED indicators; also blinks for low battery warning, completion of rewinding and dark slide inserted.