The Leica IIIf was Leitz's (later Leica) first 35mm camera body for screw mount lenses with built-in synchronization. It succeeded the Leica IIId, which was a rare variant of the Leica IIIc. Built-in sync means that, unlike its predecessors, the IIIf didn't need an optional rework for flash photography. The camera has a coupled rangefinder and a viewfinder designed for use with a 50mm lens. The camera has an M39 lens mount and cold shoe flash mount.