When the Optical Axis of the Objective Mirror strikes the flat mirror dead center and is reflected out the side right down through the dead center of the Ocular Lens System the telescope is Collimated.
There are two ways to collimate the telescope on this page: 1) Shift the Flat Left until the center of the flat intercepts the orange colored beam, and rotate the flat through an additional 2 degrees so that it makes a 47 degree angle with the telescope tube's main axis instead of a 45 degree angle. 2) Rotate the Objective Mirror forward 2 degrees to the left.
The second method is best, because the light path is shorter. This will result in a brighter image. This also makes the optical axis of the telescope coincide with the geometric axis of the telescope,- fitting the description of a truly collimated telescope as defined at the begining of this section.