Tele Vue 101mm f/5.4 Apo Nagler-Petzval Refractor # TV-NP101is

For 30 years, Tele Vue has pushed the boundaries of Apo refractors to the recognized pinnacle of performance. Backyard Astronomer's Guide said of the NP101: "optics don't get any better than this." No wonder Sky and Telescope rated the NP101 tops and selected it as the test instrument for its landmark review of the SBIG STL11000 CCD camera. The "is" versions of the Tele Vue NP101 and NP127 retain the exemplary wide field and planetary visual capability while adding new features to make imaging easier and more flexible.

Tele Vue was determined to make the NP series optically, mechanically, and functionally as perfect as possible for imaging up to 50mm diagonal chips without penalty to its near ideal visual operation.

The NP101 (540mm, f/5.4, 4") maintains its optical specifications yet with a redesigned 4-element optical system. Larger rear lens groups absolutely minimize vignetting in formats up to 50mm diagonal. For these large chips an optional field corrector was developed.

To take full advantage of the larger lenses, Tele Vue developed a larger focuser and draw tube having a 3" front aperture and 2.4" rear aperture. This eliminates any restriction of the larger diameter converging light cone. They build and test the rack and pinion focuser to hold 12 lbs. of weight, yet still permit extremely fine focusing control via a 10:1 dual speed pinion assembly. This new draw tube also permits quick change from visual to imaging operation and allows full camera rotation without focus change. In addition, it has the capability to correct for any residual focal plane tilt.

To maintain squareness to the optical axis while changing camera orientation, the draw tube has four lock screws that tighten against a taper on the "imaging insert" ring. This insert is threaded to accept Tele Vue's new Imaging System accessories including large diameter extension tubes, optical accessories, and camera and CCD attachments, all with mating threads.

Tele Vue has been known for producing visual instruments "even better than you imagined." They aim to achieve the same with their imaging equipment.