Celestron C90 User Manual

What next?
With your spotting scope firmly attached to a stable platform, you are ready to attach the standard
accessories and begin using your spotting scope.
THE C90 SPOTTING SCOPE
This section covers the correct set up and operating procedures for your Celestron C90 spotting scope and
includes information on visual and photographic observations. The C90 spotting scope uses a combination
of mirrors and lenses to produce an image. Such an optical system is known as a compound lens. This
particular design, known as a Maksutov-Cassegrain, is one of the most compact and rugged optical systems
on the market today. The basic C90 (#81031) comes standard with the following accessories:
•
25mm Eyepiece .96” (40x)
•
8x20 Erect Image Finderscope
•
45° Erect Image Diagonal - .96”
•
Photo Tripod Adapter block
•
Lens Caps
Celestron also offers model #81027 which include the following accessories:
•
26mm Plossl Eyepiece 1-1/4” (38x)
•
8x20 Erect Image Finderscope
•
45° Erect Image Diagonal .96” to 1-1/4”
•
Photo Tripod Adapter Block
•
Lens Caps
All models have multicoated corrector lenses. Model #81031 has
the standard glossy black paint finish while model #81027 is rubber covered.
Take a few minutes to study the diagram on the following page to help familiarize yourself with
the various parts of your spotting scope for set up and ongoing use.

Celestron C90 Specifications

General

Optical Design	Maksutov-Cassegrain
Focal Length	1250 mm
Focal Ratio	f/13.9
Aperture	90 mm
Eyepiece Barrel Diameter	1.25"
Mount Type	Not included (OTA only)