Tele Vue 3″ Big Paracorr Type-2
The Tele Vue 3″ BIG Paracorr Type-2 was designed to extend the optical benefits of the Paracorr to amateurs & professionals using CCD formats as large as 52mm diagonal and paraboloids as fast as f/3. The back focal length of the 3″ Paracorr has been extended to 80mm to allow placement of additional accessories in the optical path. The body of the Big Paracorr is 5.1″ long, and is topped with a “stop” flange having 3.40″-24 pitch threads to mount camera adapters and spacer tubes.
All Newtonian telescopes can benefit from using a Tele Vue Paracorr (Parabola Corrector) to eliminate coma in the image. One aspect of optimizing this correction is the distance of the eyepieces focus point (field stop location) to the last surface of the Paracorr lens (within a small +/- tolerance of course). Typical eyepieces used with fast Newtonians can have field stop locations differing by as much as half an inch. To accommodate for the differences, Tele Vue developed the “Tunable Top.” The “Tunable Top” permits optimized aberration control for all Tele Vue eyepieces and many others, by simply loosening a screw and rotating the Tunable Top. The eyepiece barrel height raises and lowers, allowing you to maintain the proper field stop to Paracorr lens distance.