Explore Scientific AR102 f/6.5 Air-Spaced Doublet Achromat Refractor Telescope

  • Aperture: 102 mm (4-inch).
  • Focal Ratio: f/6.5.
  • Focal Length: 663 mm.
  • Package includes a precision two-speed focuser, a 99-percent Reflective 2-inch Diagonal Mirror, and an 8x50 Finder Scope.


  • Sale
  • Regular price $549.99

More on the Way* We do not currently have this in stock, but is a common item we carry. More are likely on the way as the manufacturer allows.
Free Shipping
Add to Wishlist
Already have gear? Trade it in for cash or new equipment.

Accessories Added

OPT Telescope Expert

Want Help?

Ask Our Telescope Experts


Explore Scientific AR102 f/6.5 Air-Spaced Doublet Achromat Refractor Telescope

The Explore Scientific AR102 Air-Spaced Doublet Refractor is a classic air-spaced, crown-and-flint, doublet achromatic refractor with superior-class optical figure, in a short (f/6.5) focal length design. Like its two larger brothers, the AR127 and the AR152, these optics produce stunning images of deep-sky objects and planets. Their price is a small fraction to that of comparable aperture apochromatic refractors making them an extreme value.

The Explore Scientific AR Series is equipped with standard hardware that includes a precision two-speed focuser, a 99-percent reflective 2-inch diagonal mirror, dew shield and an 8X50 Finder Scope. Be confident that the quality and design of these telescopes are meant for many years of use and is endorsed by its Explore Scientific Lifetime Warranty!




Exceptional Optics

Its collimatable lenses are fully multi-coated to eliminate light scatter and maintain image contrast. Although you may never need to adjust optical alignment, the AR Series allows for collimating the lens set should the telescope ever require it.


Universal Mount

Explore Scientific’s Universal Mounting Plate is made from extruded aluminum for added strength. The mount fits on many popular equatorial and Alt-Az mounts, including mounts supplied by Explore Scientific, Celestron, Vixen and others. Adjustment screws and locking bolts to allow adjustments to position the angle of the telescope when it is placed on its mount.


8X50 Finderscope

The Explore Scientific 8X50 Finder Scope provides a true 6-degree field of view. Its coated optics provide a bright high-resolution image so that many faint stars and nebulosity can be detected for precise aiming.


Two-Speed Focuser

A standard single-speed focuser, can be put out of focus from a simple nudge. As a standard on all Explore Scientific AR Series, a two-speed Crayford-style precision focuser is included. With tension adjustment and lock to hold perfect focus, one knob works for fast focusing while the other works on fine focusing.


Comfortable, Incredible Diagonal

The purpose of a diagonal is to securely hold your eyepiece and to give you a comfortable viewing angle. Provided as standard equipment, Explore Scientific's 2-Inch Dielectric Diagonal incorporates a light-weight, one-piece diagonal body that securely cradles the polished diagonal flat mirror, ensuring precision alignment. Ultra-high reflective coatings (99-percent reflective) composed of multiple thin layers of dielectric material delivers maximum light output.


OPT Product Number: ES-DAR102065-01 



Aperture102 mm (4")
Camera/Eyepiece Connection2 Inch Nosepiece
Dawes Limit1.14 arcseconds
Focal Length663 mm
Focal Ratiof/6.5
Free ShippingYes
Limiting Magnitude12.5
ManufacturerExplore Scientific
Optical DesignDoublet
Resolution1.14 arcsec
Tube Diameter101 mm
Tube Length698 mm (25.5") with Dew Shield
Tube Weight11.5 lb (5.2 kg)


  • Explore Scientific AR102 f/6.5 Air-Spaced Doublet Achromat Refractor Telescope.
  • Cradle Rings with Handle and Universal Saddle Plate.
  • Two-Speed Focuser 2.0-inch I.D.
  • 8x50 Finder Scope.
  • Dew shield.
  • Dielectric-Coated 99-percent Reflective 2-inch Mirror Diagonal with 1.25-inch Adapter.




Customer Reviews
5.0 Based on 2 Reviews
Write a Review Ask a Question
  • Reviews
  • Questions
Thank you for submitting a review!

Your input is very much appreciated. Share it with your friends so they can enjoy it too!

Filter Reviews:
Scott F.
United States

I have only had it out once, and the waxing moon was out as well. That being the case, I looked at the moon at about 27x. It was visually stunning. There was just a hint of color along the edge of the crescent. Crater detail was excellent, especially along the terminator. I can't wait to get it under dark skies. Great value, if you don't need perfection.


Purchased the Explore Scientific 102mm 4 AR Achro. about month ago as a grab and go scope...I do own TMB 100mm 4 APO / TMB 80mm signature series 3.1 APO both absolutely superb optical instruments .. For star parties....public outreach how can you go wrong...didn't expect much as to performance.. How wrong I was....the optical quality stunned me...planetary, deep sky, lunar , double stars , were first rate...sharp superb contrast delivered ....Saturn was spectacular with incredible ring and planetary detail...it was showed it's metal with lunar views....Venus was stunning... Yes some colour aberration as to be expected but minor and very acceptable...This scope can be used right out of the box..no OTA here ....dielectric 2 diagonal... Finder scope..tube rings...handle....how can you ever go wrong for the price..... Rings