There are three major group adjustments:
1) those
that adjust the objective mirror so that its optical axis of symmetry coincides
with the central axis along the telescope's length;
2) those that center the flat
within the telescope tube and adjust its angle with respect to both the objective
and the ocular;
3) those that center the eyepiece's mounting over the flat, so
that the eyepiece's axis of symmetry will be at right angle's to the objective's
axis of symmetry.
The first group usually has six set
screws. The second group has one set screw and three pivot screws, while the last group may use
five set screws. These will differ on different telescopes.