This medium focal length 12mm Celestron X-Cel LX Series six-element eyepiece is usable for high quality medium to medium high magnification observing and imaging with any scope type, under virtually any seeing conditions.This Celestron X-Cel LX 12mm eyepiece uses a new six-element fully-multicoated optical system to provide a wide 60° field of view. This medium focal length/long eye relief Celestron X-Cel LX eyepiece is usable with any scope type, under virtually any seeing conditions - from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)
With short focal length refractors it is a low power eyepiece. With the 430mm focal length Astro-Tech AT72EDII, for example, it gives you 37x and a 1.62° field more than three 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 high magnification observing with long focal length refractors, reflectors, or catadioptric scopes. On a 7" Maksutov, for example, it yields 222x. This is an excellent magnification for planetary and close-up lunar observing, particularly when the high contrast of the eyepiece is combined with the high contrast of the Maksutov.
It's a good choice for medium to medium high magnification observing with long focal length refractors, reflectors, or catadioptric scopes - even under average seeing conditions. Its 12mm focal length is nearly ideal for an f/10 Schmidt-Cassegrain, providing a 0.12mm exit pupil that very closely matches the resolution of the scope to that of your eye. Its performance makes it a much better choice as a second eyepiece than merely doubling the power of most scopes' standard 25-26mm eyepiece with a Barlow.
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 fill its 0.35 degree field with such a scope.) Smaller globular clusters appear vivid and nearly three-dimensional. It is also very good for medium power viewing with short focal length refractors and fast focal ratio Dobsonian reflectors.
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 12mm comes with dust caps for both ends of the eyepiece and a bolt-type plastic storage case.
