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10a
10b
Proper Collimation
You have achieved proper collimation when the central shadow and the bright inner diffraction ring are concentric
with the bright outer diffraction ring, and the thin concentric dark ring (in between these two bright rings) extinguishes
uniformly and simultaneously as you slowly pass through focus (see Figure 9). Proper collimation yields a star image
diffraction pattern that is concentrically similar just inside and outside of focus. In addition, proper collimation delivers
the optimal optical performance specifications that your telescope is built to achieve.
WARNING: If you cannot collimate your SCT or EdgeHD using the collimation screws, do not attempt to make any
other adjustments to the optics or mechanics of the telescope! Doing so will not only likely put your telescope further
out of alignment, it will also void your warranty. Instead, contact Celestron Technical Support by submitting a ticket here:
celestron.com/pages/technical-support. Your telescope may need to be returned to Celestron for warranty evaluation
(or paid repair, if the warranty has expired).
10. Confirm that the diffraction pattern's central shadow and inner bright ring
have moved closer to the center relative to the bright outer ring.
a. If the central shadow and inner ring are now further de-centered, try
loosening the collimation screw instead of tightening it. Remember to re-
center the star in the field of view after each adjustment.
b. If the central shadow and inner ring have moved closer, continue to make
adjustments in the same way until the shadow and inner ring are as centered
as they can get using that collimation screw. Remember to re-center the
star in the field of view after making each adjustment.
NOTE: If you notice while making adjustments that one of the collimation
screws becomes very tight, slightly loosen the other two collimation
screws by an equal amount. This will relieve pressure on the screw that
was tight, and you should be able to continue to make adjustments
by tightening the screw. Conversely, if you notice that the collimation
screw becomes too loose when loosening it, tighten the other two
screws (refer to Figure 8).
11. If the central shadow and inner ring are still not centered relative to the outer
ring when centered in the field of view, you will need to make adjustments
to one of the other collimation screws. Go back to Step 6 and repeat the
process. This time, you will make adjustments to a different collimation screw.
SCT & EDGEHD COLLIMATION GUIDE |
Fig. 9
7
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