Many amateurs find Barlow lenses to be useful accessories to their eyepiece collections. A Barlow is fitted into the focuser first and the eyepiece is inserted into it. The Barlow may double or triple the magnification of any given eyepiece at the cost of some light loss and image degradation. But, with a carefully chosen range of eyepiece focal lengths, the Barlow can effectively double your collection. Barlows have gotten over the years.
Eye relief is the distance from the eyepiece where the full field of view is visible.
This is especially important to eyeglass wearers who won t be able to see the full field of view with these eyepieces if they must wear glasses to observe. Barlows provide an added benefit here because the eye relief of a 26mm eyepiece and a 2x Barlow will be longer than the equivalent 13mm eyepiece alone. The DSTs are provided with one of two types of mounts altitude-azimuth or equatorial. To view an object simply point the telescope and view. When the object drifts out of the field of view due to the Earth s rotation both axes must be adjusted to compensate.