This Astro-Tech 18mm Paradigm Dual ED is an excellent medium to medium low power eyepiece for lunar observing, encompassing globular clusters, picking up detail in emission and reflection nebulas, etc. This 18mm focal length is a good choice for filling in the gap between the 25/26mm eyepiece that comes standard with most telescopes and a high power planetary/binary star splitting eyepiece. It is usable with any telescope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)
With a short focal length refractor it is a medium to low power eyepiece well suited to scanning the crowded star clouds of Sagittarius. For example, with the 430mm focal length f/6 Astro-Tech AT72ED it provides 24x, a field five times as wide as the full Moon, and a 3mm exit pupil that is excellent for rich field observing and revealing large nebulas.
It is also a good choice for medium power observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8" f/10 catadioptric, for example, it yields 111x, with a 0.54° field. This is a very useful magnification for observing compact planetary nebulas and globular clusters, as well as lunar observing. Its high contrast makes observing small features along the lunar terminator a nightly delight as the terminator creeps across the face of the Moon.
The six lens/four group design and two ED (Extra-low Dispersion) glass elements of the 18mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page - high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm. Combined with the twist-up eyecup design, the good eye relief makes it a sensible choice for eyeglass wearers.
This new Astro-Tech 18mm Paradigm Dual ED eyepiece will make your nightly views of the heavens sharper, clearer, and more entrancing than ever before. The Paradigm will change your mind about how much truly high-end optical performance not much money can buy.
