Above is the camera I probably use more than any other camera I own, and I own a bunch of them. It’s a Leica IIIg 35mm film camera with a Leicavit trigger winder and an external viewfinder to allow the use of the 3.5cm Nikkor lens mounted on it (the native viewfinder only accommodates a 50mm perspective). It needs no batteries because it has no electronics. It is purely mechanical; not even a light meter to suggest proper exposure. Of course, being completely mechanical, it has no automation. You set shutter speed and f-stop, you wind and rewind the film by hand with a knurled knob. To focus you look through one window (the rangefinder) to gain focus and then move your eye to a second window (the viewfinder) to frame your shot.
I don’t possess a IIIg but I do own its immediate predecessor, the IIIf (with the smaller viewfinder) and the screw-mount IIIg’s contemporary, the Leica M3. Both are great cameras, from the rather quirky IIIc with its fiddly film loading procedure, to the M3 which is still a thoroughly usable film camera which can compete in results with the latest MPs and M7s, although at an entirely manual level.