| This 2-element Barlow has superb sharpness to match that of TeleVue eyepieces. Despite being “merely” an achromatic system, good design gives it better color correction at the edges of the field than some 3-element “apochromatic” Barlows. It is fully multicoated, with blackened lens edges and internal antireflection threading for excellent contrast. Its barrel is threaded for standard 1.25" filters. There's an undercut safety groove in the barrel that helps hold the Barlow in place should the focuser thumbscrew accidentally loosen. A captive thumbscrew (that can't be lost in the field) holds your eyepieces in place. It has a 3.75" length that allows it to be used in star diagonals. This TeleVue is parfocal with TeleVue Plössls below 32mm in focal length, so you won’t have to do any major refocusing as you change from an eyepiece alone to an eyepiece/Barlow combination. It is optically corrected down to f/4 for use with fast f/ratio reflectors, but will provide excellent performance with any scope type. | 
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