ABSTRACT
The cameras ISO setting controls how much or little the sensor data is electrically amplified. The aperture controls how much light is emitted through this small hole in the lens and the shutter speed determines the amount of time light is permitted to excite the sensor. The two shutter technique for exposures faster than the maximum sync speed disallows conventional flash use because the traveling slit never offers a time when the shutter is completely open, and accordingly, never offers a time when the sensor could be exposed with a flash burst. The default setting for every camera is front-curtain sync and most users never change. It is especially well-suited for still subjects. With high-speed sync, flash can be used at all the shutter speeds of Canons and Nikons as well as all other cameras. High-speed sync allows flash use at wide apertures in bright light, no matter how fast the shutter speed, a former impossibility for flash photography.
