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. For the large surface of the meniscus lens, clean only a small area at a time, using a fresh lens tissue on each area. Never reuse tissues.

Specifications

#9820 Apex 90mm OTA

Optical design: Maksutov-Cassegrain

Aperture: 90mm

Effective focal length: 1250mm

Focal ratio: f/13.9

Central obstruction diameter: 29mm

Primary mirror coating: Aluminum with overcoat

Meniscus lens coating: Anti-reflection multi-coatings on both sides of lens

Eyepiece adapter: Accepts 1.25” format accessories, camera t-threads

Eyepiece: 25mm Sirius Plossl, fully coated with multi-coat- ings, 1.25” format

Magnification with supplied eyepiece: 50x

Actual field of view with supplied eyepiece: 0.96°

Diagonal: 45° correct-image diagonal, 1.25” format

Near focus (with supplied eyepiece and diagonal): Approximately 13.5 feet

Finder scope: 6x magnification, 20mm aperture, correct- image, achromatic, 6.2° field

Optical tube mounting block: Fits standard photo-style tri- pods

Case: Deluxe carry case for optical tube included

Weight: 3.7 lbs

Length: 10.5” (without eyepiece or diagonal attached)

#9823 Apex 102mm OTA

Optical design: Maksutov-Cassegrain

Aperture: 102mm

Effective focal length: 1300mm

Focal ratio: f/12.7

Central obstruction diameter: 31mm

Primary mirror coating: Aluminum with overcoat

Meniscus lens coating: Anti-reflection multi-coatings on both sides of lens

Eyepiece adapter: Accepts 1.25” format accessories, camera t-threads

Eyepiece: 25mm Sirius Plossl, fully coated with multi-coat- ings, 1.25” format

Magnification with supplied eyepiece: 52x

Actual field of view with supplied eyepiece: 0.92°

Diagonal: 45° correct-image diagonal, 1.25” format

Near focus (with supplied eyepiece and diagonal): Approximately 11 feet

Finder scope: 6x magnification, 26mm aperture, correct- image, achromatic, 6.3° field

Optical tube mounting block: Fits standard photo-style tri- pods

Case: Deluxe carry case for optical tube included

Weight: 4.8 lbs

Length: 12.0” (without eyepiece or diagonal attached)

#9825 Apex 127mm OTA

Optical design: Maksutov-Cassegrain

Aperture: 127mm

Effective focal length: 1540mm

Focal ratio: f/12.1

Central obstruction diameter: 39mm

Primary mirror coating: Aluminum with overcoat

Meniscus lens coating: Anti-reflection multi-coatings on both sides of lens

Eyepiece adapter: Accepts 1.25” format accessories, camera t-threads

Eyepiece: 25mm Sirius Plossl, fully coated with multi-coat- ings, 1.25” format

Magnification with supplied eyepiece: 62x

Actual field of view with supplied eyepiece: 0.77°

Diagonal: 45° correct-image diagonal, 1.25” format

Near focus (with supplied eyepiece and diagonal): Approximately 27 feet

Finder scope: 6x magnification, 26mm aperture, correct- image, achromatic, 6.3° field

Optical tube mounting block: Fits standard photo-style tri- pods

Case: Deluxe carry case for optical tube included

Weight: 8.6 lbs

Length: 14.5” (without eyepiece or diagonal attached)

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Orion instruction manual #9820 Apex 90mm OTA, #9823 Apex 102mm OTA, #9825 Apex 127mm OTA