V112712
3
Figure 3: On the left is the 2” adapter for the CDK12.5 attached to the Secondary Spacer and the Ronchi
Ocular. On the right is the 2” adapter for the CDK17, the CDK20 and the CDK24 attached to the
Secondary Spacer and the Ronchi Ocular.
Step 1, Rough Collimation:
a.
Put the Secondary Spacer into the 2” adapter. The 2” CDK12.5 adapter has
thumb screws, and the 2” CDK17/20/24 Adapter has two 8-32 set screws which
requires a 3/32 Allen wrench.
b.
Insert the 2” adapter into the telescope focuser.
c.
Insert a low-power 1-1/4” eyepiece into the secondary spacer (25mm to 40mm).
d.
Point the telescope at a bright star.
e.
Defocus the star until it becomes a donut-like ring. If the donut hole appears well
centered in the donut, proceed to Step 2.
f.
If the donut hole is not centered, adjust the collimating screws on the back of the
secondary mirror so that the defocused star moves in the direction of the fat side
of the donut, as shown in Figure 4. Re-center the star and repeat this process until
the donut hole looks centered as shown in Figure 5. See below for details on how
to adjust the collimating screws.
Figure 4: An example of what you would see through a low-power eyepiece for an out-of-focus, out-of-
collimation telescope. To collimate this telescope you would adjust the secondary collimating screws so
that the out-of-focus star moves in the direction of the arrow.
