Orion EON 90mm ED Triplet

The Orion EON 90mm ED Triplet Apochromatic Carbon Fiber Refractor is the newest in the company’s line popular EON “apo” refractors.

Orion EON 90mm ED TripletThe fully multi-coated 90mm (3.5″) triplet lens assembly has a focal length of 540mm, for a f/6 focal ratio. One lens element is made from FCD-100 extra low dispersion “ED” glass by Hoya (Japan), which does a masterful job of minimizing chromatic aberration. Contrast is maximized with multiple internal knife-edge baffles that prevent off-axis reflections.

The Orion EON 90mm ED Triplet offers a glossy carbon fiber optical tube which provides high tensile strength and thermal stability as the temperature changes. It is accented with red and black anodized machined aluminum fittings.

The extendable dew shield thwarts moisture build-up on the lens and blocks unwanted off-axis light. When the dew shield is retracted the telescope measures just 17-3/4″ in length. It fits perfectly in the included hard carry case.

The Orion EON 90mm ED Triplet includes a 2.5″ dual-speed, hybrid rack-and-pinion focuser with 10:1 fine focus control. As the company notes, ‘In our tests the focuser was able to hold 19.5 lbs. of payload without drawtube slippage – so it will definitely hold even a heavy imaging train.” The focuser has 90mm of drawtube travel and a backfocus distance of 147mm from the 2″ accessory collar – sufficient to accommodate a camera and the component accessories in an imaging train.

The focuser can be rotated in two places, allowing camera framing to be set independently from positioning of the focus knobs at the desired orientation. Both the 2″ accessory collar and 1.25″ adapter feature a twist-tight locking mechanism. The focuser is also equipped with a dovetail finder scope base that accommodates optional Orion finder scopes and guide scopes.

The company also noted, “We tested the EON 90mm ED Triplet with the Orion Field Flattener for Small Telescopes and were pleasantly surprised how flat the field was even with a full-frame camera. Only slight star elongation was evident at the edges of the 36mm x 24mm frame. With an APS-C camera sensor you’d be hard-pressed to see any.”

The EON 90mm ED Triplet comes with two CNC-machined hexagonal tube rings with multiple threaded holes on the sides for extra accessory mounting possibilities. A carry handle is bolted to the top of the tube rings, which doubles as an accessory rail. The included Vixen-style dovetail mounting bar is 9.6″ long and fits any compatible mount saddle. The solidly built EON 90mm ED Triplet weighs in at 9 lbs., 12.4 oz. So it is easily supported by a mid-sized mount.

In addition to its imaging capabilities, if you choose to swap out a camera for an eyepiece and diagonal for some real-time observing you’ll find that it makes a fine instrument for wide-field visual examination of nebulas and other deep-sky fare. Add a Barlow lens to boost the power and you will also enjoy crisp, vivid views of the major planets and the lunar surface.

Youi can learn more about the Orion EON 90mm ED Triplet here.

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