| The 22mm focal length of this Astro-Tech 70° Field AF Series 2" eyepiece is designed for impressive wide field observing with any telescope. It will give you brilliant low power views with a small fast focal ratio refractor or large Dobsonian reflector, as well as sharp and detailed medium power views with a long focal ratio refractor or big catadioptric. It is truly excellent for medium magnification nebula and globular cluster observing, as its high contrast makes it easier to resolve subtle detail in planetary and emission nebulas and its sharpness across the field makes globular clusters vivid and nearly three-dimensional.
An f/4.5 Dobsonian will yield a wide 4.88mm exit pupil, for bright images of nebulas and galaxies and for rich field scanning of the star clouds in Sagittarius. With shorter focal length refractors, such as the Astro-Techs or TMBs, it can provide stunning wide field deep space vistas. With the 430mm focal length 72mm Astro-Tech AT72ED doublet, for example, it provides 19.5x, a 3.66mm exit pupil, and a huge 3.6° field. With the 504mm focal length 80mm TMB-80 Signature Series triplet apo, it provides 22.9x, a 3.5mm exit pupil, and a very wide 3.05° field. On both scopes, the fields are six to seven times as wide as the full Moon, for spectacular wide field views of large galaxies and nebula remnants.
The 17mm eye relief of this 22mm Astro-Tech is ideal for those who must wear eyeglasses when observing due to astigmatism. Vignetting will be minimal for eyeglass wearers, although the very wide field may require some moving of the head from side to side to see the entire field, even for those who don’t wear glasses.
This Astro-Tech comes with dust covers for both ends of the eyepiece and a plastic bolt-type eyepiece container.
The wide field optical performance of this 22mm Astro-Tech would be exceptional at any price. At its actual (and very sensible) price, it is truly outstanding. Well corrected for all aberrations, high in contrast, flat and sharp across its entire 70° field, this Astro-Tech is an extraordinary value. We feel that this Astro-Tech 70° Field AF Series eyepiece equals or surpasses the performance of exotic designs costing twice its very reasonable price. It would be a welcome addition to any astronomer’s observing kit.
|
Printer friendly version
Email page link to a friend
Do you have a question about this product?
