Orion Telescopes & Binoculars
Post Office Box 1815, Santa Cruz, CA 95061
Customer Support Help Line (800) 676-1343 • Day or Evening
Remember that the higher the magnification you use, the dim-
mer the image will appear. So stick with low power when
observing deep-sky objects because they’re already very faint.
6. Care and Maintenance
If you give your telescope reasonable care, it will last a life-
time. Store it in a clean, dry, dust-free place, safe from rapid
changes in temperature and humidity. Do not store the tele-
scope outdoors, although storage in a garage or shed is
OK. Small components like eyepieces and other acces-
sories should be kept in a protective box or storage case.
Keep the objective lens cap on when the front of the tele-
scope when it is not in use.
Your Explorer 90 requires very little mechanical maintenance.
The optical tube is aluminum and has a smooth painted finish
that is fairly scratch-resistant. If a scratch does appear on the
tube, it will not harm the telescope. If you wish, you may apply
some auto touch-up paint to the scratch. Smudges on the
tube can be wiped off with a soft cloth and a household clean-
er such as Windex or Formula 409.
Cleaning the Optics
Any quality optical lens tissue and cleaning fluid specifically
designed for multi-coated optics can be used to clean the
telescope’s objective lens as well as the lenses of the eye-
pieces and finder scope. Never use regular glass cleaner or
cleaning fluid designed for eyeglasses. Before cleaning with
fluid and tissue, however, blow any loose particles off the
lens with a blower bulb or compressed air, or lightly brush
the lens with a soft camel hair brush. 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.
7. Specifications
Optical tube: seamless aluminum
Objective lens diameter: 90mm (3.5")
Objective lens: achromatic doublet, air-spaced, optical glass
elements
Objective lens coating: fully coated with multi-coatings
Focal length: 910mm
Focal ratio: f/10
Eyepieces: 25mm and 10mm Sirius Plössls, fully coated,
1.25" barrel diameter, threaded for filters
Magnification: 36x (with 25mm), 91x (with 10mm)
Focuser: metal, rack-and-pinion
Diagonal: 45° correct-image, 1.25" barrel diameter
Finder scope: 6x magnification, 26mm effective aperture,
achromatic, crosshairs, correctly oriented image
Mount: altazimuth
Tripod: aluminum, adjustable
One-Year Limited Warranty
This Orion Explorer 90 AZ 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.
