Canon T90 - Exposure

Exposure

Eight exposure modes are available. Program AE (Auto-Exposure) mode puts exposure control completely in the hands of the camera. Variable Shift Program AE allows the photographer to bias the camera towards narrow aperture with three Wide Angle settings, or fast shutter speed with three Telephoto settings as well as the standard mode. For more manual control, Aperture Priority AE and Shutter-Speed Priority AE allow the photographer to set one exposure variable manually while the camera chooses the other.

In either of the latter two modes, a Safety Shift feature allows the camera to adjust the "fixed" parameter if it can not obtain a correct exposure otherwise. For example, in Aperture Priority mode, if the photographer has the aperture fixed wide open to photograph a very bright scene, the correct shutter speed to expose correctly at that aperture might be faster than the camera was capable of. Safety Shift will let the camera reduce the aperture until it can achieve a correct exposure at maximum shutter speed. The Safety Shift feature can be turned on and off by pressing two buttons on the back of the camera near the base.

If no automation of exposure is desired, a Manual mode is available. In this, the camera's metering acts as a sophisticated light-meter, but all decisions are made by the photographer. For use with older lenses that do not have an automated aperture diaphragm, Stopped-down Aperture Priority AE or Stopped-down Manual can be used; these instruct the camera that the currently set aperture will be the taking aperture, and to therefore adjust the metering calculations accordingly. Finally, a Flash AE mode is available for flash photography.

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