ONE of the most precise mechanisms in every camera whether mirrorless or conventional DSLR is the focalplane shutter. This is the mechanical part of a camera that controls the amount of time the light is allowed to pass through and expose the sensor.
The sound that you hear when your camera takes a shot is not the audible sound you hear in your cellphone but it’s actually the movement of mechanical pieces opening and closing the window just before the sensor. The focalplane shutter is one of the three exposure controls you can adjust when controlling the amount of light passing through your camera.
Shutter speed is not dependent on your lens but your camera body. This means that even if you change from one lens to the next, you’ll still have the same shutter speed options.”