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Explore Scientific AR102 f/6.5 Doublet Refractor w/ Twilight I Mount

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  • Regular price $579.99

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  • Aperture: 102mm (4")
  • Focal Ratio: f/6.5
  • Focal Length: 663mm
  • Great value and high optical quality achromatic doublet refractor
  • Comes on the Twilight 1 Mount Alt-Azimuth


Explore Scientific AR102 f/6.5 Doublet Refractor w/ Twilight I Mount

The Explore Scientific AR Series telescopes are classic air-spaced, crown-and-flint, doublet achromatic f/6.5 refractors with a superior-class optical figure. Whether you choose the AR102 (4"), AR127 (5") or AR152 (6") model, you will be impressed by the stunning images revealed to you at the eyepiece, and all at a small fraction of the price you'd pay for a comparably sized apochromatic refractor.

Designed to handle the rigors of public star parties and educational outreach, the Explore Scientific AR Series telescopes come with heavy-duty, high-quality components, including a 2" dual-speed Crayford-style focuser, a one-piece 2" diagonal with 99% dielectric coatings, an 8 X 50 non-illuminated straight-thru finderscope and quick release bracket, and a cradle ring assembly with Vixen-style dovetail mount. Just add a few eyepieces and the alt-azimuth or equatorial mount of your choice and you'll be ready to discover the Universe!

Interferometric data on your newly purchased and registered Explore apochromatic refractor is available upon request from Explore Scientific after 120 days of ownership.

The Twilight I is a light-to-medium-duty alt-azimuth mount and tripod designed to quickly and easily accept small to medium sized refractors, such as the ES AR102 or Carbon Fiber 102mm, and of course, the 80mm. Lightweight, fast Newtonians will also match up nicely with the Explore Twilight I mount. As long as your telescope does not exceed 15 pounds, you are good to go, and if it does, then take a look at the Twilight II, which we'll talk about below.

The Twilight I alt-azimuth mount head is made of powder-coated aluminum and there are worm gears on both axes. The adjustable angle head can be tilted forward or back at a 45-degree angle or you can point it straight up for viewing at the zenith. Slow motion control cables are attached on the vertical and horizontal axes and are easy to turn during the night, even with gloves on, due to the over-sized knurled knobs that are attached to the end of each cable. A small wrench is included with this package, and is stored in the fork arm and held in place with a magnet. If you need to make quick adjustments to your mount, it is a snap to access the wrench and then store it safely away when done. It is a small thing, but an adjustment wrench is one less tool you will need to remember to bring with you on observing sessions!

The chrome-plated steel tripod that comes standard with the Twilight I mount has adjustable legs and a wide footprint of 42 inches, which makes the tripod more stable. A spreader bar locks against the inside of the legs to secure the tripod even further and keep vibrations to a minimum.


Aperture102 mm (4")
Focal Length663 mm
Focal Ratiof/6.5
Free ShippingYes
Limiting Stellar Magnitude12.5
ManufacturerExplore Scientific


  • 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" I.D.
  • 8x50 Finder Scope
  • Dewshield
  • Dielectric-Coated 99% Reflective 2.0" Mirror Diagonal with 1.25 " Adapter