Automatic exposure
The automatic exposure ( AE for Automatic Exposure ) is a term from photo technology and an equipment feature of modern cameras , which enables automatic exposure control by coupling the f-number and shutter . An exposure meter built into the camera is a prerequisite for automatic exposure . How it works is explained under exposure metering .
Differentiation areas
Basically, a distinction is made between three types of automatic exposure systems (the assigned letter on the operating mode dial of most cameras in brackets):
- Automatic iris or time delay ( S / Tv short for: S hutter priority / T ime v alue ): Shutter speed is preselected aperture is automatically adjusted
- Automatic timer or Metering ( A / Av short for A perture priority / A perture v alue ): shutter is selected, the shutter speed is automatically set
- Programmed or fully automatic ( P ): Aperture and shutter speed are controlled automatically by the camera.
The manual exposure control in automatic switched off is usually carried M marked.
The automatic value can be deviated from by means of an exposure correction .
Almost all modern SLR cameras have the entire range of automatic exposure controls, while simple compact cameras often only offer automatic program controls .
Older cameras, some medium format cameras and all view cameras do without automatic exposure. The aperture and exposure time must be set manually with the help of an internal or external exposure meter.