The FM10 is a mechanically (springs, gears, levers) controlled manual focus SLR with manual exposure control. It is operable without batteries, which are only required (two S76 or A76, or one 1/3N) for the light metering information system. This consists of an internal 60/40 percent centerweighted, silicon photodiode light meter linked to a center-the-LED exposure control system using vertically arranged +//– light emitting diodes (LEDs) on the left side of the viewfinder to indicate the readings of the meter versus the actual camera settings. The focusing screen also has 3 mm split image rangefinder and 1 mm microprism collar focusing aids