13
will need to make slight corrections to the telescope’s position
in order to account for the sky’s apparent motion.
appendix B:
cleaning the optics
cleaning lenses
Any quality optical lens cleaning tissue and optical lens clean-
ing fluid specifically designed for multi-coated optics can be
used to clean the exposed lenses of your eyepieces or find-
erscope. Never use regular glass cleaner or cleaning fluid
designed for eyeglasses
Before cleaning with fluid and tissue, blow any loose particles
off the lens with a blower bulb or compressed air. Then apply
some cleaning fluid to a tissue, never directly on the optics.
Wipe the lens gently in a circular motion, then remove any
excess fluid with a fresh lens tissue. Oily fingerprints and
smudges may be removed using this method. Use caution;
rubbing too hard may scratch the lens. On larger lenses, clean
only a small area at a time, using a fresh lens tissue on each
area. Never reuse tissues.
cleaning Mirrors
You should not have to clean the telescope’s mirror very often;
normally once every year or so. Covering the telescope with
the dust cap when it is not in use will help prevent dust from
accumulating on the mirrors. Improper cleaning can scratch
mirror coatings, so the fewer times you have to clean the mir-
rors, the better. Small specks of dust or flecks of paint have
virtually no effect on the visual performance of the telescope
The large primary mirror and the elliptical secondary mirror of
your telescope are front-surface aluminized and over coated
with hard silicon dioxide, which prevents the aluminum from
oxidizing. These coatings normally last through many years of
use before requiring re-coating, which is easily done.
To clean the secondary mirror, it must be removed from the
telescope. Do this by holding the secondary mirror holder sta-
tionary with your fingers (don’t touch the mirror itself) while
unthreading the Phillips head screw in the center hub of the 3-
vaned spider. Completely unthread the screw from the holder,
and the holder will come loose in your fingers. Be careful not
to lose the spring on the Phillips head cap screw.
Handle the mirror and its holder carefully. You do not need
to remove the secondary mirror from its holder for cleaning.
Follow the same procedure described below for cleaning the
primary mirror.
Figure 9.
To center the secondary mirror under the focuser, hold
the secondary in place with your fingers while adjusting the primary
screw with a Phillips head screwdriver. Do not touch the mirror’s
surface.
Figure 10.
Adjust the tilt of the secondary mirror by loosening
or tightening the three alignment screws with a small Phillips head
screwdriver.
Figure 11.
Loosen one screw on the back of the optical tube one
full turn and tighten the other screw “in the set” until tight to adjust
the primary mirror.
