Astro-Tech AT90EDT 90mm

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Astro-Tech AT90EDT 90mm f/6.7 FPL-53 ED triplet apochromatic refractor

That the performance of the Astro-Tech triplet apochromatic refractor is superb shouldn’t surprise you. Astro-Tech has quickly developed a well-deserved reputation for producing excellent small optics. However, what might surprise you is the more-than-reasonable price of this exceptional 90mm mid-sized refractor. Knowledgeable astronomers have “known” for years that you couldn’t get a true FPL-53 triplet apochromatic optical system with a collimatable lens cell in this size/focal ratio range for anywhere near this price. With this new AT90EDT, Astro-Tech is happy to prove those doubters wrong.

The use of an FPL-53 ED (Extra-low Dispersion glass) center lens element in the three-lens optical system reduces spurious color halos and fringing to vanishingly low levels for true apochromatic performance. All three lens elements are made from the finest quality Ohara glass. Ohara is well-known as Japan’s premier manufacturer of specialized optical glass.

Those exceptional optics are even more impressive when you consider the package they come in. The lens cell is fully user-collimatable in the field for peak performance. The finely-machined scope has a rotating dual speed 2.7” rack-and-pinion focuser with a microfine 11:1 fine-focusing ratio. The supplied 2” and 1.25” eyepiece holders use non-marring brass compression rings that won’t scratch your eyepiece barrels. The Astro-Tech AT90EDT has a retractable lens shade and comes in a locking aluminum-frame carrying case.

Unlike other manufacturers who skimp on production costs by putting a 90mm lens in an 80mm tube, Astro-Tech has designed and built a tube specifically for the exceptional 90mm AT90EDT triplet optics. While this may cause a slight weight penalty (the basic optical tube weighs 11.5 lbs.), the solid feel and precision build quality of the AT90EDT tube are well worth the slight extra weight.

If the Astro-Tech AT90EDT was simply a 90mm ED doublet system, it would still be fairly priced. But – a 90mm fast focal ratio triplet using true FPL-53 glass and a dual-speed 2.7” rack and pinion focuser at this price . . . is a steal!

  • 90mm f/6.67 triplet apochromatic optics using an FPL-53 ED element and all Ohara glass
  • Collimatable lens cell
  • Fully broadband multicoated, with blackened lens edges
  • Rotating dual-speed 2.7” rack-and-pinion focuser with 11:1 ratio fine focusing
  • Non-marring 2” and 1.25” brass compression ring eyepiece holders
  • Self-storing retractable lens shade/dew shield
  • Long-lasting white paint finish, with hard anodized grey trim
  • Aluminum-frame foam-fitted hard case
  • Two-year warranty

Takes +-6 Weeks to get Stock

  • Model: AT90
  • Shipping Weight: 25lbs
  • 20 Units in Stock
  • Manufactured by: Astro-Tech

This product was added to our catalog on Thursday 29 November, 2012.

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