Leica's final Barnack — the IIIg, frame-line finder, coupled RF, cloth shutter, 1957.
The Leica IIIg was the last screw-mount Barnack body in the main line, introduced in 1957 and produced alongside the newer M3. It refined the III design with a larger, brighter viewfinder carrying projected frame lines, a feature borrowed from the M system.
It is a 35mm coupled-rangefinder camera taking 39mm screw-thread lenses, with a horizontal-travel cloth focal-plane shutter, front slow-speed dial, flash sync and a self-timer. The viewfinder adds bright projected frame lines for two focal lengths with parallax indication, there is no built-in meter, and the shutter is fully mechanical and battery-free.
It suits photographers who want the most developed screw Leica with an improved finder, plus collectors seeking the final Barnack model. The brighter finder with frame lines makes it easier to use than earlier III bodies while keeping the compact screw-mount form.
Check rangefinder patch contrast and vertical alignment and confirm the projected frame lines are clear and not hazed. Test slow speeds, the self-timer and flash sync, and inspect the cloth curtains for pinholes and capping. Verify a clean mount and smooth film transport; finder condition strongly affects value.