Tele Vue TV-NP127is OTA

From 1977 to Today: The Hand-Crafted Tele Vue Legacy

Since its founding in 1977 by Al Nagler, Tele Vue has established a legacy of optical innovation, beginning with the original 5" f/4 Multi-Purpose Telescope (MPT). The TV-NP127is is a direct descendant of that Petzval concept, refined through the Renaissance, the fluorite-equipped Genesis, the SDF and the Tele Vue-101. The NP127 arrived in 2003 at an even faster f/5.2, and the NP127is of 2006 added a more robust, larger focuser with standard 10:1 reduction. Tele Vue telescopes are built start to finish by a single technician in Chester, New York, with quality checks at several critical steps.

Objectives are spaced in 0.1mm increments and rotated and positioned within the cell, and each focuser is hand-fitted, which is how Tele Vue assures diffraction-limited performance. The telescope carries Tele Vue's 5-year warranty.

The 127mm f/5.2 Nagler-Petzval APO System

The optical heart of the NP127is is a 4-element, 2-group apochromatic system based on the Nagler-Petzval design. This configuration uses two widely spaced, air-spaced doublets, the Petzval arrangement that produces a flat focal plane; the forward pair sits in a stainless steel cell inside the sliding dew shield. The fully multi-coated 127mm objective has an aperture gain of 329 compared to a 7mm exit pupil and achieves a photographic resolution of 277 line pairs per mm, resolving details down to the 0.9 arc-second Dawes limit.

Unlike many doublets and triplets that need a field flattener for imaging, the NP127is is flat-field by design; the LCL-1069 is added only for 35mm and larger formats or pixels under 6µm. The rear doublet is larger in diameter than on the previous NP127 and adds illumination at the edge of the field, which matters for large chips that are sensitive to light fall-off.

The 2.4" Focuser with a 12 lb Payload

The TV-NP127is uses a 2.4" rack-and-pinion focuser with a 10:1 Focusmate dual-speed reduction for precise control. The drawtube has a 3" input and 2.4" output, which keeps the focuser light while covering the largest commercial chips with a 52mm diagonal, and it is rated for a 12 lb payload.

• Threaded Connections: The included Imaging System Adapter (ISA) provides solid threaded connections between all Tele Vue Imaging System components.
• Tilt Adjustment: The end ring is pre-set parallel to the focal plane and can be jacked and locked with jam screws to compensate for tilt seen in your images, using the Allen keys supplied.
• Tension Control: Two tension screws on the focuser body adjust drawtube resistance, while three lock screws on the end ring secure the 2" Accessory Adapter or Imaging System Adapter; even when tight, the knobs can still drive the draw tube.

A 14.5 lb OTA with Field-Ready Features

The TV-NP127is is built for both performance and practicality. The optical tube weighs 14.5 lbs and measures 33.5" long, on a 5" powder-coated aluminum tube.

Every mechanical detail is designed for field use. The captive sliding metal dew shield protects the objective from stray light and moisture, while the screw-on metal lens cover provides secure protection during transport. The included custom hard-shell case holds the telescope with its standard accessories, with a cutout for an optional Starbeam; the telescope in its case weighs 28 lbs.

A 4° Maximum Field for Expansive Views

With a 2" 55mm Plössl at 12x or a 41mm Panoptic at 16x, the TV-NP127is frames a 4° true field, enough for the Andromeda Galaxy (M31) or most of the Veil Nebula (NGC 6960/6992). The Petzval layout keeps that field flat, which is why Al Nagler first used the design for testing eyepieces.

Tele Vue eyepieces cover 12x to 330x, and 300x is the maximum recommended power. At low power the fast f/5.2 ratio gives large exit pupils (up to 10mm with the 55mm Plössl), which suits nebula filters on faint emission targets.

Imaging at f/5.2 and f/4.2 with Full-Frame Coverage

The "is" in NP127is stands for Imaging System, and this telescope is optimized for astrophotography with sensors up to 52mm diagonal. It can be configured for several focal lengths and image scales with Tele Vue's own correctors.

• Prime Focus (660mm, f/5.2): At its native focal length, the telescope produces a 50mm image circle. For sensors with pixels smaller than 6µm or for 35mm (full-frame) and larger formats, the optional LCL-1069 Large Field Corrector is recommended, requiring a precise back focus of 2.64" (67mm).
• Reduced Focal Length (528mm, f/4.2): The optional NPR-2073 0.8x Reducer transforms the scope into a faster f/4.2 instrument. This setup is optimized for full-frame (43mm diagonal) sensors and requires a 68mm back focus for color cameras or a 50mm back focus for monochrome imaging with filters.
• Increased Focal Length: For planetary or small target imaging, use the 2x and 4x Powermates with their T-ring adapters for the Moon, planets and double stars.

The MRS-5000 Rings and Accessory Ecosystem

Proper mounting is critical, and the optional MRS-5000 5" Mount Ring Set is the recommended solution for the TV-NP127is. These rings are lined with thin felt to prevent scratching the tube and allow for easy fore-aft balancing by loosening the bat-handle screws. The rings attach to a base plate compatible with Tele Vue's Gibraltar HD5 alt-azimuth mount or, via an adapter, Vixen-style mounting saddles.

The top of the ring set features machined channels with #10-32 threaded holes for attaching a wide range of accessories. The mounting plate also takes Tele Vue's Vixen Mount Adapter (AVT-1011) for Vixen-style equatorial mounts, and the BPL-1098 bottom plate is available separately.

• Finderscopes: Tele Vue particularly recommends the Starbeam (SRT-2010) unit power finder, which attaches to the tube rings and has a cutout in the hard case. Traditional 50mm finders can be mounted using the Quick Release Universal Finder Bracket.
• Solar Observing: The Sol-Searcher (SSF-1006) attaches to the tube rings and is the only finder Tele Vue approves for locating the Sun, used only with professional solar filtering rigidly secured in front of the objective; remove the Starbeam first.

NP127is vs. NP101is: A 58% Aperture Advantage

The closest sibling to the NP127is is the NP101is. While both share the same 4-element Nagler-Petzval design philosophy and Imaging System focuser, they serve different priorities for observers and imagers.

• Aperture and Resolution: The NP127is, with its 127mm objective, has 58% more light-gathering area than the 101mm NP101is. This translates directly to brighter images of faint deep-sky objects and higher resolving power for planets and double stars.
• Focal Length and Image Scale: At 660mm (f/5.2), the NP127is provides more image scale than the 540mm (f/5.4) NP101is, making it better suited for medium-sized galaxies and planetary nebulae. The NP101is, in contrast, offers a slightly wider maximum visual field of 4.9°.
• Portability: The NP127is optical tube weighs 14.5 lbs, requiring a more substantial mount than the lighter, more compact NP101is. If portability comes first, the NP101is is the lighter tube; if aperture comes first, the NP127is is the NP101is' big brother with 58% more lens area and faster speed.