SHARPSTAR 13028HNT 130mm f/2.8 Hyperbolic Astrograph 5,1″

The SharpStar 130mm F/2.8 HNT is a true Formula 1 car for astrophotography, far ahead of its competitors. Ultra-fast optics with f / 2.8 light and an ultra-light carbon fiber tube concealing the most advanced technological solutions, leave no doubt that such a comparison is absolutely right.

Sharpstar takes the initiative in launching the very first 130mm hyperbolic Newtonian reflective telescope with an extremely-fast focal ratio of f/2.8(15028HNT). It has garnered a quite large following since its advent. Not indulging in this great achievement, Sharpstar keeps the creativity and dynamism, introducing 13028HNT to our customers, which has a same focal ratio but a slightly smaller aperture size. 13028HNT, with a hyperbolic primary mirror, produces round and sharp stars within the full-frame and supports 44mm image circle. Compared with the focal  ratio of f/4, 13028HNT can attain the same image quality while save almost half of the exposure time. Besides, due to its compact and concise design of the telescope tube, it will certainly create a stir again in the market.

The primary mirror is made of Pyrex-alike glass PZ33. The thermal expansion coefficient is smaller than ordinary glass. The dielectric multilayer coating makes the primary mirror obtain a highly reflective ability up to 97%. The minor axis of the secondary mirror is 65mm, enabling sufficient illumination for full-frame imaging. It’s worth mentioning that, the corrector is renovated to a two-refractive-lens set, one of which is an ED glass, aiming to simplify the optical system while enhancing the power in aberration correction.

The telescope tube is totally made of high-end carbon fiber material, so the weight of the telescope can greatly lessen and the overall appearance may artistically build up. All the component parts are from CNC constructed metals. The pair of tube rings feature pierced design. It may increase the production cost, but will absolutely offer extraordinary customer experience because of its lightweight and detail-oriented design concept.

The focuser is a 2.5″ rack-and-pinion device. It’s equipped with coarse as well as fine adjustment hand knobs to further improve the focusing precision. The focuser is tapped with M63 thread which can be switched into a more general M48×0.75 thread with a proper adapter ring(included). Thus the users may have a wider range of options in connecting other astronomy accessories to the focuser. The back-focus is standard 55mm(starting from the base of the mounting thread on the adapter ring’s housing), which is user-friendly for newcomers.

A versatile handle and a standard Vixen-style dovetail plate are also included in the 13028HNT package, which may be of convenience for users to attach other potential accessories and to place the telescope on various equatorial mounts.

The optical system of this astrograph is a Newtonian reflector with an aperture of 130 mm and a focal length of 364 mm. The main mirror is made of PZ33 glass, which, like Pyrex glass, has a lower coefficient of thermal expansion. In addition to the careful selection of the mirror material, the manufacturer also took care of covering it with a high-efficiency dielectric coating, thanks to which it reflects up to 97 percent of the incident light.

An important element of the optics is also the built-in field flatness corrector. Its construction is a doublet with an air gap, in which one of the lenses is made of low-dispersion (ED) glass.

In addition to impeccable optical parameters, the SharpStar 130 mm F/2.8 HNT is characterized by high quality and precision of mechanical parts. A solid rack & pinion extractor allows the installation of even heavy astronomical cameras, and the mounting rings and Losmanda rail made in the CNC technology guarantee full stability of the tube.

The most important features of the SharpStar 130mm F/2.8 HNT Astrograph

• professional high-luminous hyperbolic astrograph
• main mirror covered with a high efficiency dielectric coating
• two-element corrector with a lens made of low-dispersion glass
• 55 mm back focus, compatible with most cameras and camcorders available on the market
• a solid hood that guarantees the linearity even with a heavy load
• ultra-light and durable tube made of carbon fiber

Simple camera adaption via the screw thread of the focuser

With such a high resolution and fast optics, a screwed adaption of the camera is necessary. This prevents tilting and thus blurred stars at the edge.

The 2.5″ R&P focuser has a M48x0.75 male thread in addition to the M63x0.75 female thread. The working distance from this thread is exactly 55 mm. This corresponds, for example, exactly to the distance required by an SLR camera and the matching T-adapter. Astro cameras, such as those from ZWO, are also already supplied with an adapter kit to M48, which takes exactly this distance into account.

The Hypergraph convinces by its short design. For incident light, such as lanterns and similar stray light, it makes sense to use a flexible dew shield. A good dew shield not only reduces the risk of dew, it also prevents stray light from entering the tube. This also improves the contrast of the image.

This is how we hand over the hypergraph to the star friend:

The hypergraphs must undergo a complete optimization and check after transport. We have to invest several hours of time in each telescope, only in this way you will get an operational telescope. The individual steps are:

•  Removal of the main mirror cell and tightening of all screws, as they are usually loose.
• Optimizing the fit of the main mirror in the cell – not too tight and not too loose.
• Cleaning the main mirror and the inside of the tube.
• Checking and optimization of the focuser.
• Collimation of the whole system and check of the collimation stability.
• Creation of the manufacturing protocol and preparation for shipment.