| This 15mm Vixen Lanthanum eyepiece is a medium focal length eyepiece designed to have exceptionally long eye relief for eyeglass use. It uses seven optical elements in four groups to achieve an exceptionally long and eyeglass-friendly 20mm eye relief that is typically two to three times longer than that of similar focal length Plössl eyepieces. The 15mm Vixen eyepiece is usable with any telescope type, under virtually any seeing conditions – from fair to superb. With short focal length refractors, it’s a low power/wide field eyepiece. With long focal length refractors, reflectors, or catadioptric scopes it is excellent for medium high magnification lunar, planetary, and globular cluster observing. On an 8" catadioptric, for example, it yields 133x. Its long eye relief makes it a much better choice as a second eyepiece for eyeglass wearers than merely doubling the power of most scopes’ standard 25-26mm eyepiece with a Barlow.
The optical performance and width of field of the 15mm Vixen are comparable to other quality eyepieces in its price range, such as a good Plössl. There is a slight loss of contrast when compared to a simpler four-element Plössl, however, due to the additional optical elements needed to achieve the long eye relief of this Vixen. The loss is minimal though, and this 15mm Vixen would still have the benefit of much longer eye relief (particularly at a price half that of other 20mm eye relief eyepieces in this focal length range). |
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