Self-timers

At the time retardants that can trigger the shutter after a period of several seconds were not included in the unit, there were triggers that functioned as a cable release. Once the accessory attached to the release button or the hole for the cable release, traveling back clockwork, advanced out of the accessory and returned to the arming button or orifice and triggered the camera. The photographer had temsp to get in front of the camera before it takes the picture (or other utility ....). More traveling back mechanism, plus the trigger delay was long.