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Newtonian collimation views as seen through the focuser.
Figure A: If you cannot see the entire primary mirror reflected in the
secondary mirror, the secondary mirror will need adjustment. To do
this, adjust the secondary collimation screws by alternately tightening
and loosening them until the outer edge of the primary mirror is
reflected in the secondary mirror.
Figure C: With both mirrors aligned you should see the silhouette of
the secondary mirror positioned in the center of the primary mirror.
You should see your eye reflecting back at you from the center of both
mirrors. Collimation is now completed.
Night Time Star Collimation
After successfully completing daytime collimation, night time star collimation can be done by closely
adjusting the primary mirror while the telescope tube is on its mount and pointing at a bright star. The
telescope should be set up at night and a star's image should be studied at medium to high power (30-50
power per inch of aperture).
13), then it may be possible to correct this by re-collimating only the primary mirror.
Procedure
(Please read this section completely before beginning)
To star collimate in the Northern Hemisphere, point at a stationary star like the North Star (Polaris). It can
be found in the north sky, at a distance above the horizon equal to your latitude. It's also the end star in
the handle of the Little Dipper (Ursa Minor). Polaris is not the brightest star in the sky and may even
appear dim, depending upon your sky conditions. Observers in the southern hemisphere should aim the
telescope at a bright star near the celestial pole.
Prior to re-collimating the primary mirror, locate the collimation screws on the bottom of the primary mirror
cell at the end of the telescope tube. These three screws are to be adjusted one at a time. Normally,
motions on the order of an
maximum required.
turbulence, so it is best to let the optics cool to thermal equilibrium for at least an hour after sunset for best
results.
14
Figure B: Now that you can see the entire primary mirror reflected in
the secondary mirror, you will notice that the secondary mirror is not
perfectly centered in the primary mirror. To correct this, you must
adjust the primary collimation screws located at the bottom of the
primary mirror cell (see Figure 12).
If a non-symmetrical out-of-focus pattern is present (see figure
1
/
turn will make a difference, with approximately a
8
This method of collimation is particularly sensitive to atmospheric and heat
1
3
/
to
/
turn being the
2
4
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