a | b |
| c | d |
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Figure 8. This illustration show the telescope pointed in the four cardinal directions (a) north (b) south (c) east (d) west. Note that the tripod and mount have not been moved; only the telescope tube has been moved in the R.A. and Dec. axes.
6. Collimating the Optics
Collimating is the process of adjusting the mirrors so they are aligned with one another. Your telescope’s optics were aligned at the factory, and should not need much adjustment unless the telescope is handled roughly. Accurate mirror alignment is important to ensure peak performance of your telescope, so it should be checked regularly. Collimating is relatively easy to do and can be done in daylight.
To check optical alignment, remove the eyepiece and look down the focuser drawtube. You should see the secondary mirror centered in the drawtube, as well as the reflection of the primary mirror centered in the secondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror, as in Figure 9a. If anything is
drawtube
Reflection of primary mirror clip
b.c.
a.
d.e.
Figure 9. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (b) With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (c) Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible. (d) The secondary mirror is correctly aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned, the “dot” will be centered, as in (e).
9 | 9 |
