About the TeleVue NP101is APO - Imaging System Refractor Telescope... For 30 years, TeleVue Telescope has pushed the boundaries of APO refractors, as well as TeleVue Telescope Eyepieces, to the recognized pinnacle of performance. We were gratified but not surprised that Backyard Astronomer''s Guide said of the NP101: "optics don''t get any better than this." No wonder Sky and Telescope rated the TeleVue NP101is APO - Imaging System Refractor Telescope 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-60, 102i, NP101 and NP127 retain the exemplary wide field and planetary visual capability while adding new TeleVue Telescope features to make imaging easier and more flexible. TeleVue Telescope 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. How? By applying the developments created for the Tele Vue-60is to the new TeleVue NP101is APO - Imaging System Refractor Telescope and NP127is and then going beyond. Combine with a TeleVue Mount for excellence in astrophotography. The TeleVue NP101is APO - Imaging System Refractor Telescope (540mm, f/5.4, 4") and NP127 (660mm, f/5.2, 5") maintain their optical specifications yet with redesigned 4-element TeleVue Telescope optical systems. Larger rear lens groups absolutely minimize vignetting in formats up to 50mm diagonal. For these large chips an optional field corrector was developed so the corners of the newly brightened edges would virtually be as perfect as the center of the field. Next, to take full advantage of the larger lenses, TeleVue Telescope 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 into the TeleVue NP101is APO - Imaging System Refractor Telescope to hold 12 lbs. of weight, yet still permit extremely fine focusing control via a 10:1 dual speed pinion assembly. This new TeleVue Telescope 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 and accepts a "position stop" for our digital micrometer to allow repeatable focus measurement to 0.0001". To maintain squareness to the optical axis while changing camera orientation, the draw tube on the TeleVue NP101is APO - Imaging System Refractor Telescope has four lock screws that tighten against a taper on the "imaging insert" ring. This insert is threaded to accept TeleVue Telescope'''s new Imaging System accessories including large diameter extension tubes, TeleVue Optical Accessories, and camera and CCD attachments, all with mating threads. The 10:1 dual speed focuser custom designed by Starlight Instruments and standard on the TeleVue NP101is APO - Imaging System Refractor Telescope, provides extremely sensitive focus adjustment, measurable with the optional Digital Micrometer Kit to better than 1/10,000". Also, the optional Focusmate Driver permits electronic motor control of the focusing process. The TeleVue Telescope Focusmate Driver has direction push-buttons and adjustable speed. A tap on the button permits vibration-free focusing in steps as small as approximately 0.0005". The Focusmate Driver can be remotely computer controlled with optional Focusmaster Computer Interface. Don'''t forget, we carry plenty of TeleVue Accessories, too! Look for TeleVue Telescope Eyepieces and TeleVue Telescope Filters for visual observers - as well as TeleVue Finderscopes and TeleVue Dioptrx! TeleVue NP101is APO - Imaging System Refractor Telescope Features... Dual speed knobs are on the right side of the telescope only, the 1:1 left side knob is the classic 5-hole Tele Vue style. All knobs have knurled rubber grip rings New draw tube also permits quick change from visual to imaging operation and allows full camera rotation without focus change. As perfect as possible for imaging up to 50mm diagonal chips without penalty to its near ideal visual operation. Larger focuser and draw tube having a 3" front aperture and 2.4" rear aperture. Insert 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. Package Includes: Enlarged focuser with 3" entrance aperture and 2.4" exit aperture, Focuser body has brass clamp ring with 2-lock knobs, Accessory end-ring with tilt capability and 4-lock knobs, Imaging insert threaded for Imaging System components, 2" accessory insert for visual or other 2" accessories, Focusmate dual-speed focuser 10:1, Sliding metal dew shield, Screw-on metal lens cover and Hard-shell carry case TeleVue NP101is APO - Imaging System Refractor Telescope Specifications... Type: APO (Nagler-Petzval) Refractor Elements/Groups: 4/2 Objective (mm): 101 Focal Length (mm): 540 Focal Ratio (f/#): 5.4 Drawtube/Focuser: 2.4-inch, Focusmate dual-speed rack/pinion Length OTA (inch): 25.5 Weight OTA/Std. Config (lbs): 10.65 / 10.65 Maximum Visual Field (deg.): 4.9 (with 2-inch 55mm Plossl) Maximum Recommended Power (x) 250 TeleVue Product Number: NPI-4057
