This Celestron X-Cel LX 18mm eyepiece uses a new six-element fully-multicoated optical system to provide a wide 60° field of view. This medium focal length Celestron X-Cel LX is usable with any scope type, under virtually any seeing conditions - from fair to superb.
An f/4.5 Dobsonian will yield a 4mm exit pupil, putting it into the rich field observing range. With short focal length refractors, it's a low power, very wide field eyepiece. With the 430mm focal length Astro-Tech AT72EDII, for example, it gives you 24x and a 2.5° field that is five times as wide as the full Moon. This is well suited for observing open clusters such as the Pleiades and large nebulas such as the Lagoon. Both will fit nicely into its field when used with the Astro-Tech AT72EDII, with a framework of black sky around the objects to set them off.
This Celestron is also quite good for medium magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On a 7" Maksutov, for example, it yields 148x and a 0.41° field. This is an excellent magnification for close-up lunar observing, where the Moon will more than fill the eyepiece field at this magnification, particularly when the high contrast of the eyepiece is combined with the high contrast of the Maksutov.
Its full multicoatings provide high contrast that makes it a good choice for resolving detail in planets and planetary nebulas, while its edge-to-edge sharpness makes it well-suited for lunar, planetary, and globular cluster observing with an SCT. (Some of the larger globulars, such as M13, will nearly fill its 0.54° field with such a scope, but will still show a nice framework of black sky around the object.
It has a twist-up rubber eyecup and a usable eye relief of 16mm, for virtually unvignetted use with eyeglasses. A no-slip rubber grip ring provides a secure and comfortable grip when handling or changing eyepieces in cold weather. It is parfocal with the other X-Cel LX models so it will require little refocusing when changing between focal lengths.
The Celestron X-Cel LX 18mm comes with dust caps for both ends of the eyepiece and a bolt-type plastic storage case.
