| This 1.25" 2x achromatic Barlow lens can be used visually, but the eyepiece holder portion also has integral T-threads so it can be used as a T-adapter for lunar and terrestrial photography. The physically short (2.9”) Barlow fits into the rack and pinion focuser drawtube of most equatorial refractors and reflectors. It can also be used in the 1.25" visual back or eyepiece holder of most Schmidt-Cassegrain or Maksutov-Cassegrain telescopes. However, use with these scopes is not particularly recommended as the weight of the camera will be held in place by only the thumbscrew on the eyepiece holder, and your camera might wind up on the ground if the temperature drops and the metal of the thumbscrew contracts and loses its grip on the Barlow.
Photographically, the Barlow doubles the effective focal length and focal ratio of the telescope and acts as a transfer lens to project a two times enlarged image onto the film plane of your camera for close-up lunar and terrestrial photography. It can also be used with many reflectors that do not have a moveable primary mirror or with refractors that do not have enough focuser in-travel to reach focus with a conventional camera adapter. Some vignetting may be visible with very short focal length telescopes. Needs optional T-ring for photographic use. |
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