Sky-Watcher 3.5" f/13.9 Maksutov-Cassegrain Telescope (OTA Only)

Sky-Watcher 3.5" f/13.9 Maksutov-Cassegrain Telescope (OTA Only)

Sky-Watcher 3.5" f/13.9 Maksutov-Cassegrain Telescope (OTA Only)

B&H # SK90MMMCOTA MFR # S11500
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Expected availability: 7-14 business days

Product Highlights

  • 3.5" / 90mm Aperture
  • 1250mm Focal Length, f/13.9 Focal Ratio
  • Limited-Diffraction Optical System
  • Anti-Reflection Fully Multicoated Optics
  • Internal Primary Mirror Focusing System
  • 25mm & 10mm 1.25" Eyepieces
  • 1.25" 90° Star Diagonal
  • Red Dot Finderscope
  • 1/4"-20 Tripod Mount
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  • 1Description

Similar to their Schmidt cousins, this 3.5" f/13.9 Maksutov-Cassegrain Telescope from Sky-Watcher exchanges the front corrector plate with a convex meniscus lens which not only eliminates the need for periodic collimation, but the nature of the lens requires a smaller secondary mirror which limits obstruction and increases contrast. The Mak-Cass optical path results in a slower focal ratio and narrower field of view versus a similar Schmidt-Cass, but the optical benefits makes this an ideal scope for planetary and double-star observation.

The scope is outfitted with a 1.25" back focus and to get users started, Sky-Watcher includes a 25mm eyepiece with a 1.25" barrel that produces 50x power, a 10mm for 125x, and a 90° star diagonal for viewing with the OTA pointed at or near the celestial zenith. The OTA is offered here without a mount or tripod for users that have a platform, or want to use it as part of a dual-OTA set up for star-parties or observation/imaging rigs. It is outfitted with a 1/4"-20 mount for use with most tripods, or to attach an optional dovetail plate for mounting on equatorial or alt-az mounts. This OTA's compact form-factor belies its observation power and resolution and is ideally suited as a grab-and-go option for quick observation sessions or heading out to remote locations.

Optical Performance
  • 3.5" / 90mm aperture
  • f/13.9 focal ratio
  • 1250mm focal length
  • Front convex meniscus lens corrects spherical and chromatic aberrations, and comas (off-axis aberration) across the entire field of view
  • Smaller secondary mirror versus Schmidt-Cassegrains reduces obstructions and increases contrast
  • Anti-reflection fully multicoated optics reduce light loss for increased image brightness
  • Requires user-supplied mount and tripod
  • 1/4"-20 tripod mount
  • OTA and accessories weigh 3.6 pounds
  • Internal primary mirror focus
  • 1.25" diameter visual back accepts larger eyepieces
  • Large rubberized focus knob
Optical Accessories
  • 25mm 1.25" eyepiece yields 50x power
  • 10mm 1.25" eyepiece yields 125x power
  • Red dot finderscope
  • 1.25" 90° star diagonal
UPC: 050234115001
In the Box
Sky-Watcher 3.5" f/13.9 Maksutov-Cassegrain Telescope (OTA Only)
  • 90° Star Diagonal, 1.25" Barrel
  • 25mm Eyepiece, 1.25" Barrel
  • 10mm Eyepiece, 1.25" Barrel
  • Red dot Finderscope
  • Limited Two-Year Warranty
  • Table of Contents
    • 1Description
    Optical Design Maksutov-Cassegrain
    Aperture 3.5" / 90 mm
    Focal Length 1250 mm
    Focal Ratio f/13.9
    Eyepiece Barrel Diameter 1.25"
    Diagonal 90° star
    Finderscope Red dot
    Tripod None
    Mount Type 1/4"-20 tripod mount
    Power Source N/A
    Optical Tube Dimensions Not specified by manufacturer
    Weight 3.6 lb / 1.6 kg
    Packaging Info
    Package Weight 8.35 lb
    Box Dimensions (LxWxH) 22.4 x 10.1 x 9.8"

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