From essential accessory to Leica logo bearer, to world’s most losable lens protector
Oskar Barnack got it right the first time when he affixed the c.1914 Ur-Leica’s flat metal lens cap directly to the front flange of its collapsible lens by means of a slotted-head machine screw. A brutally inelegant solution perhaps, but unlike 99% of lens caps before or since it’s virtually impossible to misplace. And to deploy it you simply swing the permanently attached (but easily removable) cap in place over the front of the lens.
The Ur-Leica’s pivoting lens cap was no mere window dressing—it was an essential component of the camera because its cloth focal-plane shutter was not self-capping. In other words, if you didn’t cover the lens while winding the film to the next frame, simultaneously cocking the shutter, the open slit between the shutter curtains would pass over the film again, causing it to be light-struck and ruining at least one and possibly 2 frames.
The exquisite prototype Null-Serie (0-Series) Leica of c.1923, and the remarkably faithful O-Series Replica of 2000 have similar non-self-capping focal plane shutters and both employ the inconvenient but workable solution of having leather lens caps tethered to a little sheet metal bracket on the front of the body with a stout braided cord. To prevent the dreaded “unintended re-exposure effect” you always have to remember cap the lens while you wind to the next exposure, to which I can attest from personal experience, is a damn nuisance.