Check out this article on Sky and Telescope by Donald Bruns on the Televue NP101is.
The Tele Vue-NP101is 4inch, 101mm APO Refractor Telescope from Tele Vue, a recognized leader in the field of high end imaging telescopes, is an absolute work of art. Tele Vue's craftsmanship and optical excellence is legendary and this APO challenges any other brand for precision and quality. The Tele Vue-NP101is refractor presents a 540mm focal length with a focal length f/5.4 in a finely crafted instrument designed for CCD astro-photography. The Nagler-Petzval (NP) design uses widely spaced doublet lensing to produce a flat focal plane over a relatively narrow field of view. The "is" (for imaging system) design yields an instrument capable of addressing the very specific mechanical architecture required for high quality astro-photography. The Tele Vue-NP101is is as optically near perfection as possible for CCD imaging cameras boasting up to 50mm diagonal chips, while still providing breathtaking results as a premium Visual Instrument.
"CCD cameras have challenged telescope optics beyond anything ever placed at the focal plane. I knew our APO objectives were up to the challenge, and with the proper tweaks would be extraordinary tools for the imager. With Tele Vue Imaging System ("is") telescopes, we have refined our instruments and optional equipment beyond anything a CCD chip has seen. We started small (literally) in 2005 with the Tele Vue-60is and available Digital Micrometer Kit. Achieving critical acclaim with the 60is, we were encouraged to further develop "is" telescopes and accessories to maximize aperture, real field coverage and performance, and to make the processes easier for the imager". - Al Nagler
For 25 years, Tele Vue has pushed the boundaries of APO refractors, as well as 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 NP101 tops (May & June 2002) and selected it as the test instrument for its landmark review of the SBIG STL11000 CCD camera (July 2004). The "is" versions of the Tele Vue- 60, 102i, NP101 and NP127 retain the exemplary wide field and planetary visual capability while adding new features to make imaging easier and more flexible.
NP101 (540mm, f/5.4, 4") maintain their optical specifications yet with redesigned 4-element 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.
In order to take full advantage of the larger lenses, a non-vignetting focuser was developed to prevent any restriction of the larger converging light cone. The draw tube has a 3" front aperture and 2.4" rear aperture. 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 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 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.
- TV – NP101is 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
Included Accessories TV - NP101is
- 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 10:1 dual-speed focuser
- Sliding metal dew shield
- Screw-on metal lens cover
- Hard-shell carry case
|Name||TeleVue - NP-101is 101mm, f/5.4 APO (Nagler-Petzval) Refractor - Imaging/Visual|
|Manufacturer Part No||NPI-4057|