TeleVue NP101is

The TeleVue NP101is telescope has been designed to be as optically, mechanically, and functionally perfect as possible for imaging up to 50mm diagonal chips without penalty to its near ideal visual operation.

The TeleVue NP101is (540mm, f/5.4, 4") maintains its optical specifications with re-designed 4-element optical systems. Larger rear lens groups completely 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.

To take full advantage of the larger lenses, TeleVue 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. The rack and pinion focuser was built and tested to hold 12 lbs. of weight, whilst permiting incredibly fine focusing control via a 10:1 dual speed pinion assembly.

This draw tube also facilitates quick change from visual to imaging operation and makes it possible for full camera rotation without focus change. Additionally, it has the capacity to correct any residual focal plane tilt and accepts a "position stop" for TeleVues digital micrometer enabling repeatable focus measurement to 0.0001".

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.

The Focusmate 10:1 planetary ball type reduction focuser provides extremely sensitive focus adjustment, measurable with the optional Digital Micrometer Kit to better than 1/10,000".

The optional Focusmate Driver allows for electronic motor control of the focusing process. The 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 Focusmaster Computer Interface.


  • 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 Plössl)
  • Maximum Recommended Power (x) 250

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