Automatic exposure
1938 (Kodak Super Six-20)
A light meter linked to the camera’s controls set the exposure by itself. The Kodak Super Six-20 of 1938 was the first; electronics made it universal by the 1970s and 80s.
How it began
After the light meter, photographers still had to set the camera by hand. Kodak’s Super Six-20 of 1938 linked a selenium meter to the aperture, setting it automatically; it was expensive and few were sold.
How it works
The meter measures the light. In shutter priority, the photographer picks a shutter speed and the camera sets the aperture; in aperture priority it is the other way round; in program mode the camera picks both. Early systems used needles and mechanical linkages, and later ones electronics.
Why it mattered
It removed the most common reason for a failed photograph. Cheap “electric eye” cameras of the 1960s, and the Canon AE-1, made automatic exposure normal.
Limits and what replaced it
A meter is fooled by snow, backlight or dark scenes. Through-the-lens and multi-zone metering, and today’s live view of the actual exposure, made it more reliable.
Today
Almost every camera can set exposure automatically, now from the sensor itself.