The SharpStar 13028HNT hyperbolic Newtonian astrograph delivers premium performance at a remarkably affordable price. This compact 130mm f/2.8 reflector uses innovative optical design and multiple precision elements to provide a 44mm image circle that fills 36mmx44mm full-frame sensors with an astonishing 6.9 degree field of view. This is the perfect instrument for astrophotographers looking to capture large nebulae, galaxies, and star fields in the Milky Way.
The super-fast f/2.8 focal ratio arises from the integration of a 130mm hyperbolic primary mirror with enhanced aluminum coatings with 97% reflectivity. Sharpstar used Pyrex-like PZ33 glass for the mirror substrate to ensure good thermal performance. This hyperbolic mirror is far more difficult to grind and polish compared to standard parabolic primaries, but it delivers reduced aberrations and field curvature at the edge of the wide field of view. The large secondary mirror spans 65mm along the minor axis and passes light through a two-element corrector lens (with one ED element) to deliver a crisp, sharp, and bright image over the entire 44mm image circle with minimal chromatic aberration and outstanding field flatness.
The SharpStar 13028HNT is engineered and constructed to be durable for field use, yet portable and lightweight enough to make it easy to mount and handle. The scope uses an 15.5″-long carbon fiber tube and CNC aluminum fittings for a precision fit and finish. The 2.5” dual-speed rack and pinion focuser offers handles larger cameras and accessories without slipping. The focuser also comes with a 1.25″ eyepiece holder for using the scope with smaller cameras or even with eyepieces for visual observing. The backfocus is 55mm from the M48x0.75 threaded adapter so Nikon/Canon DSLRs will readily come to focus when used with a wide 48mm camera-specific T ring (not included). The SharpStar 13028HNT includes with both a Vixen style and Losmandy style dovetail plate, an innovative and attractive carry handle on top, and a hard-sided carrying case.
The total weight of the SharpStar 13028HNT with all accessories is just 4.3kg (9.5 lbs), making it an ideal match for many medium-capacity equatorial mounts.
PLEASE NOTE: This precision astrograph has extremely fast optics and tight alignment tolerances. We recommend collimation each time it is transported or jostled. There is a link to collimation instructions under the “Additional Resources” tab. You will require a 1.25″ Cheshire collimator and a 1.25″ laser collimator.
- Focal length of primary mirror：364mm
- Focal ratio of primary mirror：f/2.8
- Primary mirror type：Hyperbolic reflective mirror
- Primary mirror material：PZ33（similar to Pyrex glass）
- Corrector：two-element air-spaced refractive lenses（including one ED glass）
- Minor axis of secondary mirror：65mm
- Image circle：44mm
- Field of view：6.9 degree
- Main tube material：High-end carbon fiber
- Main tube outer diameter：174mm
- Main tube length：394mm
- Net weight：3.2kg
- Gross weight：4.3kg（including protective cap, tube rings, handle and Losmandy-style dovetail plate）
- Resolution：0.89 arc second
- Focuser：2.5″ with fine-adjustment
- Limiting visual magnitude：12.3