Mechanical shutters: focal-plane and leaf
1880s (focal-plane); 1912 (Compur leaf shutter)
With dry plates, exposures fell to fractions of a second. Two shutter types emerged: blinds that run across the film, and blades that open inside the lens.
How it began
Early plates needed seconds or minutes, and photographers simply removed and replaced the lens cap. The gelatin dry plate made exposures of a hundredth of a second possible, and these needed a mechanism. In the 1880s Ottomar Anschütz used a slit in a blind running just in front of the plate. In 1912 the Compur leaf shutter from Friedrich Deckel set a standard for lens shutters.
How it works
A focal-plane shutter uses two curtains: the first opens and the second follows, so a slit sweeps across the film. A leaf shutter uses blades that open and close in the lens. Each makes a series of shutter speeds, each half the one before.
Why it mattered
Shutters made action and handheld photography possible. Focal-plane shutters let lenses be changed easily and reached very short speeds; leaf shutters were quiet and worked with flash at any speed.
Limits and what replaced it
A focal-plane slit can distort fast subjects and limits flash speed; leaf shutters top out around 1/500 s. Electronic shutters avoid moving parts but bring their own distortions, which stacked sensors reduce.
Today
Both still exist; most digital cameras also use electronic shutters that switch the sensor on and off.