STEP 4: There are the circle of primary mirror, the circle of secondary
mirror, the central mark on the primary mirror, the reflection hole on the
surface of the secondary mirror and a crosshair in your field. Rotating the
secondary mirror group and using the wrench with set screws on the cross
to control the position of the secondary so that the circle of the primary
mirror is moved to be concentric with the circle of the secondary mirror
as seen through the collimating eyepiece, and the center reflection of the
eyepiece is centered over the crosshair. After this is done, make certain
that the adjustment has been locked in place though tightening the set
screws.
