The Leica M-Cable Release 20" is essential for lengthy exposure times. While the Leica M's focal-plane shutter causes little vibration when it fires, a tripod and cable release are best for longer exposure times. The remote release for the Leica M features a conical thread and is screwed into the shutter release bushing. A locking screw lets you make long time exposures at the B setting.

For exposures longer than four seconds using the Leica M7 for example, set the shutter-speed dial to B and after firing via the remote release, hold the shutter in the open position for the desired exposure using its locking screw.