9. care and Maintenance
care of the Mount and tube assembly
Give your telescope reasonable care and it will last a lifetime. Store it indoors or
in a dry garage. Do not leave the telescope outside except when using it. Keep it
covered with a plastic tarp or drop cloth to keep dust and dirt off. The optical tube
is aluminum and has a smooth painted surface that should resist scratches and
smudges. If a scratch does appear on the tube, it will not harm the telescope. If
you wish, white auto touch up paint will cover the scratch nicely. Smudges can be
wiped off with standard household cleaners such as Windex or 409. The gears on
the equatorial mount should not need to have grease applied to them except after
a long period of storage or if you have been observing in a particularly dusty site.
Apply a thin ribbon of grease (automotive bearing grease works best) just where
the worm gear mates to the gear wheel, then work the grease around the worm
and wheel by rotating the slow motion control cables.
care of the optics
Any quality “Optical” lens cleaning tissue and “Optical” lens cleaning fluid specifi-
cally designed for multi-coated optics can be used to clean the exposed lenses of
your eyepieces or finder scope. Never use regular glass cleaner or cleaning fluid
designed for eyeglasses. Always put the fluid on the tissue, never on the optics.
Use lots of tissue on larger lenses. Never reuse tissue. Don’t take eyepieces apart
for cleaning!
Always remove any dirt or grit with a light wipe with a moistened tissue, and then
re-clean with another tissue. Don’t grind dirt in! Oily fingerprints and smudges may
be removed using this method. Don’t smear dirt around; remove it gently!
cleaning First surface Mirrors
Cleaning is seldom needed (perhaps after five or ten years) and best done only
when definitely needed. Covering your telescope will prevent the mirrors from get-
ting dirty, and improper cleaning can scratch mirror coatings, so don’t be
too eager to do so. Small specks of dust or flecks of paint have virtually no effect
on performance, so don’t clean your mirror too often; it’s too much trouble for
little reason!
The large primary mirror and the elliptical secondary mirror of your telescope are
front-surface aluminized, and then overcoated with hard silicon monoxide, which
prevents the aluminum from oxidizing. These coatings normally last through many,
many years of use before requiring re-coating (which is easily done).
The diagonal mirror is more likely to require cleaning, since it is right up near the
eyepiece. It should be cleaned by blowing or brushing dust off first (do not use
canned air as it contains compounds harmful to first surface mirrors), then
cleaned with ordinary lens fluid and cleaning tissue. Be extra gentle when
cleaning first-surface mirrors, and be especially careful not to rub grit over the
surface of the mirror. (Very tiny, barely visible “sleeks” are not unusual, and do not
affect performance.)
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ed, the primary mirror reflection should be centered in your view. Within the
primary mirror reflection is the reflection of the secondary mirror (dark circle
with your eye's image/reflection within it). Center it within the primary mirror
reflection using the three phillips head bolts on the back of the primary mirror
cell. Once everything is centered under the focuser (I.E.: secondary mirror,
primary mirror reflection, secondary mirror reflection) you are done. Remember
to re-tighten the allen head bolt "locks" on the back of the mirror cell.
star test
The simplest way to see if your telescope is in collimation is by making a simple
star test. Simply center a bright star in the field of the telescope and defocus the
star image. You will see the star as a large circular disc (the image of the pri-
mary mirror) with a dark “hole” in the center of it (the shadow of the secondary
mirror). If you look closely, you will see the shadow of the single-arm secondary
mirror holder.
If the collimation is good, the “hole” in the “donut” will be exactly centered when
the image is centered in the field of the eyepiece. By making slight adjustments
to the primary mirror, you can fine-tune the collimation—putting the “hole” in the
center of the donut.
As mentioned in the section, “Cooling Your Telescope,” unstable atmosphere or
atmospheric distortions (dust in the air, air currents, etc.) will show up at higher
magnifications. If you create an out-of-focus star image, any movement visible
across the resulting “disc” is due to an unstable atmosphere. Make sure you are
not looking over buildings or any other source of heat as that will also cause this
image to become distorted.
If the movement you see is on one side of the disc, or there is a distinct slow mov-
ing bump in one section, this is an indication of tube currents. To solve this
problem, let the telescope cool down longer, or store cold (outside garage or stor-
age facility) to minimize the temperature change to reach equilibrium.
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