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Explore Scientific ED165mm f/7 Air-Spaced APO Triplet CF Refractor (OTA Only)
Explore Scientific ED165mm f/7 Air-Spaced APO Triplet CF Refractor (OTA Only)

Explore Scientific ED165mm f/7 Air-Spaced APO Triplet CF Refractor (OTA Only)

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Your Price: CAD16,999.00
Retail Price:CAD18,947.04

Your Savings:CAD1,948.04(10%)

Usually ships in 7-14 business days
Part Number:FPL53-165CF-01

Choose Options or Accessories if Applicable

Focal Extenders
Field Flatteners / Coma Corrector
Finder Scopes & Accessories
Focuser and Accessories
Cradle Rings
Filters for Visual and Astrophotography
Simulate views with this scope and various eyepieces help

Product Highlights

  • 165mm Aperture Refractor OTA
  • 1155mm Focal Length, f/7 Focal Ratio
  • Apochromatic Triplet Lens Configuration
  • Ohara FPL-53 Extra Low-Dispersion Glass
  • Proprietary EMD Enhanced Multi-Coatings
  • Heavy-Duty 3" Hexagonal Focuser
  • Vixen-Style Dovetail Plate
  • Lightweight Carbon Fiber Optical Tube
  • 90° Dielectric-Coated Star Diagonal
  • OTA Only: Mount and Tripod Required

With the largest aperture in the series, making this OTA ideal for both visual observation and astrophotography, the Explore Scientific ED165mm f/7 Air-Spaced APO Triplet CF Refractor is perfect for lunar, planetary, and deep-sky viewing. Using Ohara FPL-53 extra low-dispersion (ED) glass in an apochromatic air-spaced triplet lens configuration, with fully multi-coated optics, produces images that are clear and bright without fringing, halos, or distortion across the entire field of view, with true color rendition and high contrast. The fast focal ratio, when combined with the large aperture and superb optical performance, makes this an ideal astrograph to capture images with accurate colors and limited distortion across the entire field of view.

To handle large imaging rigs and accessories, Explore Scientific outfitted the OTA with a heavy-duty focuser to carry imaging gear and accessories. Using a traditional rack-and-pinion mechanism makes it more solid and sturdy than comparable Crayfords, while the large 3" hexagonal drawtube is stronger and less prone to flexing than conventional round tubes. When put together, the focuser, by itself, has an impressive payload capacity of 10 pounds — allowing it to comfortably carry the heaviest of astrophotography rigs with ease. A two-speed system allows for fast coarse, then precision fine focusing to ensure the most sharp and crisp views possible.

Offered here as an OTA-only option for those with reliable support systems, the carbon fiber tube weighs just 27.6 pounds, and can be supported by a wide array of mounts. A cradle ring set is included, with an integrated handle for safer setup and breakdown. A Vixen-style dovetail plate makes it compatible with a wide array of alt-azimuth, equatorial, and GoTo mounts. The cradle ring assembly also allows the orientation and position of the OTA relative to the mount to be adjusted for better balance and to avoid interference with equipment or mount. The OTA's carbon fiber construction also resists the expansion and contraction common in metal tubes when moving between extreme temperatures, which can cause the internal lens elements to move out of alignment over time, affecting the scope's ability to achieve sharp focus and causing fringing and halos.

Whether you want an OTA with uncompromising image quality, or a fast OTA that produces bright and clear images of the moon, planets, galaxies, nebulae, or star clusters, this Explore Scientific optical tube assembly is ideal.

Optical Tube Assembly
  • Over-sized 165mm (6.5") aperture is ideal for lunar and planetary viewing with the ability to see deep sky objects
  • Relatively fast f/7 focal ratio, for its size, is useful for astrophotography, as shorter exposure times are required
  • 1155mm focal length produces a fast focal ratio and less internal light diffusion for bright images and views
  • Refractor-style optical design produces less chromatic aberration than reflectors
  • Extra low-dispersion (ED) Ohara FPL-53 glass corrects chromatic aberration, for improved color rendition and contrast without halos, astigmatism, off-axis comas, and color fringing
  • Apochromatic triplet optical design virtually eliminates spherical and chromatic aberrations for views without distortion across the entire field of view, as well as accurate color representation
  • Proprietary anti-reflection EMD enhanced multi-layer coatings on all optics improve light transmission, color rendition, clarity, and contrast
  • Resolution: 0.701 arcsec, Dawes Limit
  • Carbon fiber optical tube reduces weight without sacrificing strength, and resists the expansion/contraction caused by temperature fluctuations, which can cause internal lenses to move out of alignment and affect image quality and focusing ability
  • Retractable dew shield keeps condensation off objective for clearer views — especially when moving from warm interiors and colder exteriors
Focuser Details
  • Heavy-duty hexagonal drawtube is stronger and less prone to flexing than traditional round tubes
  • Large 3" drawtube diameter ensures enough light throughput to cover large imaging sensors without vignetting
  • Rack-and-pinion system is more sturdy and stable than Crayford styles to resist flexing and increase payload capacity
  • Two-speed focusing mechanism enables fast coarse and precise fine focusing
  • 2" eyepiece holder accepts larger eyepieces and accessories
  • Heavy payload capacity of up to 10 pounds of gear
  • Optical tube assembly (OTA) only: Mount and tripod required for proper use
  • Mounting ring assembly has an integrated handle to provide more secure setup and breakdown
  • OTA placement is adjustable on mounting ring assembly for precise balancing, and for finderscope and focusing knob orientation
  • Vixen-style dovetail plate is compatible with a variety of mounts
  • Lightweight and durable carbon fiber optical tube weighs 27.6 pounds
Included Accessories
  • 2" snout and holder accepts larger eyepieces and accessories
  • 90° angle places head in a comfortable position — especially when the OTA is aimed at or near the zenith
  • Star diagonal configuration corrects view horizontally, but not vertically
  • Highly reflective dielectric-coated mirror limits light loss and pushes transmission to greater than 99%
Reducer adapter:
  • 2"-to-1.25" reducer allows the use of the more common 1.25" eyepieces and accessories
Spacer rings:
  • Set of two spacer rings allows the back-focus distance to be increased and place the focal plane directly on imaging sensors
Carrying case:
  • Hard exterior protects case during transport and storage
  • Custom-cut foam lining perfectly fits OTA and accessories
  • Reinforced edges and corners
  • Hinged carrying handle
  • Dual snap-lock latches secures and seals lid from dust
Finder bracket:
  • Pre-mounted for user-supplied finderscope


Optical Design Apochromatic air-spaced triplet refractor
Aperture 165mm
Focal Length 1155mm
Focal Ratio f/7
Eyepiece Barrel Diameter 2"
1.25" with included adapter
Diagonal 90° star
2" snout and holder
Finderscope None
Tripod None
Mount Type Vixen-style dovetail
Optical Tube Dimensions Diameter: 6.5" / 16.5 cm
Length: 52.0" / 132.0 cm, with dew shield
Length: 41.0" / 104.1 cm, without dew shield
Weight 27.6 lb / 12.5 kg

In the Box
Explore Scientific ED165mm f/7 Air-Spaced APO Triplet CF Refractor (OTA Only)
  • 2" 90° Star Diagonal
  • Eyepiece Reducer Adapter
  • Hard Carrying Case
  • 2 x Back-Focus Extension Ring
  • Limited 1-Year USA Warranty, Extendable to Transferrable Lifetime Warranty with Registration

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