Tele Vue 2x BIG Barlow 2 Inch with 1-1/4 AdapterOffered in a 2x magnification the Big Barlow is ideal for Newtonian scope owners. It will be parfocal with both 2" and 1?" eyepieces in this application. Features include threads for 48mm filters captive lock screw and full multi-coatings.Properly designed Barlows do wonderful things: They amplify power slow the telescope's f/# (improving eyepiece sharpness) and give designers the opportunity to compensate for eyepiece aberrations. Tele Vue Barlows use multi-coated high index glasses for optimum aberration correction exceptional contrast with virtually no light loss. Observed performance is aberration free even when tested with f/4 scopes. They even improve our competitor's eyepieces and telescopes!Compromise image quality in any part of the optical chain and you've compromised every part! Tele Vue product design and execution deliver consummate satisfaction. Every Tele Vue Barlow must pass the same rigorous f/4 full field testing as all our eyepieces. All Tele Vue Barlows now use brass clamp rings for secure non marring holding of eyepieces and accessories

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