Paul Jolly Photography Chapter 12.1

Quick release

I recommend you use a quick release connector between the camera and head as this speeds up the setup and lessens the chance of dropping your camera, many heads come complete with a quick release. If you have multiple cameras and holding systems keep to a single type of release so you can move between setups easily. The quick release also protects the threads in the camera and head.
quick release on camera

A quick release can also be added to telephoto lenses for fast attachment and demount. The one shown here is attached to the bottom of the camera.