The large primary mirror and the elliptical secondary mirror
of your telescope are front-surface aluminized and over-
coated with hard silicon monoxide, 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, first remove it from the telescope.
Do this by keeping the secondary mirror holder stationary with
your fingers while unthreading the center Phillips head screw in
the hub of the 3-vaned spider. The entire mirror holder will come
out of the telescope. The secondary mirror itself cannot be
removed from the holder because it is glued into place. Handle
the entire assembly carefully by the holder only; do not touch the
mirror surface. You can clean the secondary mirror in its holder
by following the same procedure described below for cleaning
the primary mirror.
To clean the primary mirror, carefully remove the mirror cell from
the telescope. This is done by removing the six screws that con-
nect the entire mirror cell to the steel tube. These screws are
located on the outside of the tube, just above the mirror
cell casting.
Now, remove the mirror from the mirror cell by first removing the
four mirror clips that secure the mirror in its cell. Use a Phillips
screwdriver to unthread the mirror clip anchor screws. Next, hold
the mirror by its edge, and remove it from the mirror cell. Be care-
ful not to touch the aluminized surface of the mirror with your
fingers! Set the mirror on a clean, soft towel. Fill a clean sink, free
of abrasive cleanser, with room-temperature water, a few drops
of liquid dishwashing detergent, and if possible, a cap-full of rub-
bing alcohol. Submerge the mirror (aluminized face up) in the
water and let it soak for several minutes (or hours if it’s a very
dirty mirror). Wipe the mirror under water with clean cotton balls,
using extremely light pressure and stroking in straight lines
across the surface. Use one ball for each wipe across the mirror.
Then rinse the mirror under a stream of lukewarm water. Any
particles on the surface can be swabbed gently with a series of
clean cotton balls, each used just one time. Dry the mirror in a
stream of air (a “blower bulb” works great), or remove any stray
drops of water with the corner of a paper towel. Water will run off
a clean surface. Dry the bottom and edge surfaces with a towel
(not the mirror surface!). Cover the mirror surface with Kleenex,
and leave the entire assembly in a warm area until it is com-
pletely dry before reassembling the telescope.
7. Specifications
SkyQuest XT10
Focal Length: 1250mm
Aperture: 250mm
Focal Ratio: f/5
Mirror Coatings: aluminum with SiO overcoat, 88% reflective
Minor Axis of Secondary Mirror: 63mm
Weight: 57.6 lbs. (tube 35.0 lbs., base 22.6 lbs.)
Tube Length: 1220mm (48")
Tube Outer Diameter: 303mm
One-Year Limited Warranty
This Orion SkyQuest XT Dobsonian Reflecting Telescope is warranted against defects in materials or workmanship for
a period of one year from the date of purchase. This warranty is for the benefit of the original retail purchaser only. During
this warranty period Orion Telescopes & Binoculars will repair or replace, at Orion’s option, any warranted instrument
that proves to be defective, provided it is returned postage paid to: Orion Warranty Repair, 89 Hangar Way, Watsonville,
CA 95076. If the product is not registered, proof of purchase (such as a copy of the original invoice) is required.
This warranty does not apply if, in Orion’s judgment, the instrument has been abused, mishandled, or modified, nor
does it apply to normal wear and tear. This warranty gives you specific legal rights, and you may also have other rights,
which vary from state to state. For further warranty service information, contact: Customer Service Department, Orion
Telescopes & Binoculars, P. O. Box 1815, Santa Cruz, CA 95061; (800) 676-1343.
Orion Telescopes & Binoculars
Post Office Box 1815, Santa Cruz, CA 95061
Customer Support Help Line (800) 676-1343 • Day or Evening
