CONTROL: By choosing the best aperture and shutter combination and leaving Auto ISO to do the work of balancing exposure, you can ensure sharp results.
These modes have been the mainstay of cameras since the days of film.
Program of course has the camera automatically choose a shutter and aperture for you, while Shutter-priority allows you to choose a shutter speed while the camera sets the aperture and Aperture-priority allows you to control the aperture while the camera matches it with an appropriate shutter speed.
