The Sharpstar 130HNT is an astrograph with the ultra fast focal ratio of f/2.8 and a focal length of 364mm. Unlike the Newtonian optical design, this telescope features a hyperbolic primary mirror, a large 65mm secondary mirror and a 2 element corrector to be placed before the focal plane. The optical design delivers a 44mm fully illuminated and corrected image circle for large sensors such as full frame (24x36mm).
The mirror is made of H-PZ33 borosilicate glass with a similar low expansion thermal coefficient to Pyrex. The enhanced aluminium mirror coating ensures a reflectivity over 96%. The large 65mm secondary mirror is rigidly kept in place by the monopiece secondary mirror spider that does not bend or twist.
The large rack and pinion 2.5" focuser can be rotated 360°and it has a reduction gear of 1:10 for precise focusing. The focuser is compatible with the ZWO EAF electronic focuser bracket. The focuser has an M54 female thread, but includes an M54 male to M48 male adapter with an optical thickness of 2.20mm. This does not count towards the backfocus, which is 55mm measured from the camera-side of this adapter.
All the lenses used in the corrector are fully multi-coated and the tube is internally blackened to reduce reflections and absorb stray light.
The tube is made of carbon fiber, the rack and pinion focusing mechanism of brass and the mechanical components are engineered to provide the best rigidity, performance and durability.