TAKE CONTROL
Controlling shutter speed
How electronic and mechanical shutters differ, and when to use them
D igital cameras started out with the sensor replacing film behind the mechanical shutter. SLR cameras use a pair of shutter curtains, the first uncovers the sensor or film, and then the second covers it at the end of the exposure. The curtains take power to drive them, and stop them, larger cameras with bigger motors and batteries can move the curtains more quickly than smaller lighter cameras. Starting, moving and stopping the curtain all takes fractions of time, but as the shutter speed increases there comes a point where the second curtain is covering the sensor before the first curtain has uncovered it.
The innards
Some recent cameras have an electronic shutter, where the image sensor’s sensitivity to light is turned on and off electronically while the shutter curtains are kept fully open. EOS R5 and R6 have a combination of physical first curtain and electronic second curtain available as standard.