OS X Use the built-in camera
If your Mac or display has a built-in iSight, FaceTime, or FaceTime HD camera, you can use it to take pictures or videos using Photo Booth, make video calls using FaceTime, or video chat with your friends and family using Messages.
Turn the camera on: A green indicator light beside the camera glows when an app that uses the camera is open.
Turn the camera off: Close the active app window. The green indicator light turns off, showing that the camera is off and video has stopped.
To learn more about using your camera with the apps mentioned, see Photo Booth Help, FaceTime Help, and Messages Help.