Secondary Mirror Adjustments:
There are three types of major adjustment to the secondary mirror: rotation, vertical centering, and tilt. If the secondary mirror (
1,
Fig. 11
) isn’t centered in the focuser drawtube (
2, Fig. 11
), please center it by using the adjustment screws
(3 and 4 Fig. 8)
. to tilt
the secondary mirror into place.
If the secondary holder appears centered in the focuser drawtube, but is not rotated to aim the beam of light through the center of
the focuser, begin by removing the secondary mirror cover
(1, Fig. 8)
by grasping it with your hand and turning it counter-clockwise.
Then tighten the center flat-head screw
(2, Fig. 8)
so that it is snug. This screw extends three internal plastic pins that are meant to
keep the secondary from rotating while you loosen and tighten the secondary retainer ring
(5, Fig. 8)
. Grasp the secondary retainer
ring and turn it counter-clockwise a few turns and then release the center flat-head screw so that the secondary mirror is free to
rotate. (Note that your telescope may also have two hex-head set screws in the sides of the secondary retainer ring that must be
released in order to free it for unthreading.) With the secondary retainer ring loosened, grasp the secondary assembly and rotate it
while looking down the center of the focuser drawtube until the reflection of the secondary mirror resembles the round shape as
seen in
Fig. 10
. Now tighten the center flat-head screw to hold the secondary mirror rotational position, and then tighten the
secondary retainer ring until it is snug. Double check the rotational position of the secondary mirror. If the adjustment looks good,
then release the center flat-head screw to release pressure on the corrector from the three plastic pins.
Vertical centering of the secondary can be adjusted by raising or lowering the secondary assembly by threading in or unthreading a
Phillips-head screw that is under the center flat-head screw
(2, Fig. 8)
. Perfect centering of the secondary mirror will appear as in
Fig. 10
. To access the Phillips-head vertical centering screw, remove the center flat-head screw by using a wide flat-head
screwdriver to unthread it from the secondary holder.
Primary Mirror Adjustments:
If the secondary mirror (
1, Fig. 10
) and the reflection of the primary mirror (
2, Fig. 10
) appear centered within the drawtube (
3, Fig.
10
), but the reflection of your eye and the reflection of the secondary mirror (
4, Fig. 10
) appear off-center, then the primary mirror
tilt requires adjusting, using the adjusting screws of the primary mirror cell (
1, Fig. 6
). These primary mirror-tilt screws are located
behind the primary mirror, at the lower end of the main tube. See
Fig. 6
. Before adjusting the primary mirror-tilt screws, first loosen
the three wide slotted primary mirror lock screws (
2, Fig. 6
) using the provided collimation tool. Then by trial and error turn the
primary mirror hex head tilt screws (which are located inside the wide slot headed screws see
1, Fig. 6
) until you develop a feel for
which way to turn each screw to center the reflection of your eye in the drawtube. (An assistant is helpful in this operation.) With
your eye centered as shown in
Fig. 7
, turn the three wide slotted head primary mirror lock screws (
1, Fig. 6
) to re-lock the tilt-angle
of the primary mirror. There is interaction between the adjustment and lock screws and it may be necessary to use both locking and
tilt screws simultaneously.
The collimation locks will hold collimation for a long period; however, collimation should be rechecked from time to time.
Fig. 14 Fig. 15
Cradle Ring Assembly and Dovetail Adjustments
The cradle rings are clamp style that secure and release with a single knob. To make adjustments for tube balance and/or eyepiece
position, release the knob on each ring (
1, Fig. 14
) so that the tube is loose enough in the rings to slide back and forth or rotate. Be
careful to hold the tube securely so that you do not lose control of it while the cradle rings are loose. Once the tube is in the desired
position, be sure to tighten each cradle ring lock knob until the tube is secure.
The dovetail saddle plate on the Comet Hunter has adjustments for cone error. On the bottom of the saddle plate are three hex
screws on each end (
1 and 2 Fig. 15
). The center screw (
1, Fig. 15
) holds the dovetail to the cradle ring, the two outer screws (
2,
Fig. 15
) allow for cone error adjustment.
1
1
2
