SharpStar 130mm f/2.8 HNT Hyperbolic Newtonian Astrograph

f/2.8 Hyperbolic Optics: 130mm Aperture at 364mm Focal Length

At the core of the 130HNT is a fast, light-gathering optical system designed for one purpose: deep-sky imaging. The 130mm hyperbolic primary mirror, made from low-expansion PZ33 glass, works in tandem with a two-element corrector to deliver sharp stars across the field. This f/2.8 focal ratio allows you to capture faint details in nebulae and galaxies with significantly shorter exposure times compared to slower f/5 or f/7 systems.

• Enhanced Coatings: Both the primary and secondary mirrors feature an enhanced aluminum coating, ensuring reflectivity greater than 96% for brighter images and better signal-to-noise ratio.
• PZ33 Primary Mirror: The Pyrex-like PZ33 mirror material minimizes thermal expansion and contraction, helping the telescope maintain focus as ambient temperatures change during an imaging session.
• Corrected Field: The corrector assembly includes an ED (Extra-low Dispersion) glass element to suppress chromatic aberration, ensuring star colors are rendered accurately without distracting halos.

44mm Image Circle for 6.9° Wide-Field Views

The 130HNT is engineered to fully illuminate a 44mm image circle, making it an ideal match for full-frame DSLR, mirrorless, and dedicated astronomy cameras. A 65mm secondary mirror ensures there is no vignetting across these large sensors. This expansive 6.9-degree field of view lets you frame enormous targets like the Andromeda Galaxy (M31) or the entire North American Nebula (NGC 7000) in a single shot.

A Rigid 4.8kg System with CNC-Machined Components

An astrograph's mechanical stability is just as critical as its optical design. The SharpStar 130HNT is built from all-metal components, featuring a rigid aluminum main tube and CNC-machined parts for the focuser, secondary bracket, and mirror cell. This construction ensures precise, repeatable collimation and minimizes mechanical flexure, even with a heavy imaging payload.

• Stable Secondary Bracket: The integrated, CNC-machined secondary mirror bracket is designed for rigidity, which not only holds collimation but also produces clean, sharp diffraction spikes on bright stars.
• 3-Point Primary Cell: The primary mirror cell features three sets of adjustment screws for precise collimation, ensuring you can align the optical system for peak performance.
• Lightweight Rings: The included tube rings have a hollowed-out design to reduce weight without sacrificing strength, bringing the total assembled weight to a portable 4.8kg.

3kg Capacity Focuser with Integrated Rotator and 55mm Back Focus

The imaging train is managed by a heavy-duty, dual-speed rack-and-pinion focuser designed to carry a payload of up to 3kg. This robust focuser can easily support a full-frame camera, filter wheel, and off-axis guider without slipping or tilting. An integrated 360° camera rotator allows you to frame your target perfectly without loosening any other components, while the standard 55mm back focus simplifies the process of connecting your camera and accessories using standard M48 spacers.

SharpStar 130HNT vs. 130mm APO Refractors: The f/2.8 Advantage

While a 130mm apochromatic refractor offers a maintenance-free, sealed optical tube, the SharpStar 130HNT provides a decisive advantage in speed. A typical 130mm APO has a focal ratio around f/7, whereas the 130HNT operates at f/2.8.

• Exposure Time: The f/2.8 system gathers light over six times faster than an f/7 system. An 1-minute exposure on the 130HNT collects the same amount of signal as a 6-minute exposure on the refractor, allowing you to complete projects in a fraction of the time.
• Field of View: With its 364mm focal length, the 130HNT delivers a much wider field of view than a 130mm refractor, which typically has a focal length over 900mm.
• Trade-off: The Newtonian design requires periodic collimation to maintain peak optical alignment, a step not needed with a refractor. However, for imagers prioritizing speed and field of view, this is a manageable trade-off for the dramatic reduction in exposure time.