SharpStar 13028HNT 130mm Super-Fast f/2.8 Hyperboloid Newtonian Reflector Telescope with Carbon Fiber Tube

Sharpstar took the initiative in launching the very first 150mm hyperbolic Newtonian reflective telescope with an extremely-fast focal ratio of f/2.8 just a few years ago. We are referring to the very popular 15028HNT that has garnered a quite large following since its advent. Not indulging in this great achievement, Sharpstar keeps on with their creativity and dynamism, and now introducing the new 13028HNT to their customers, which has a same focal ratio but a slightly smaller aperture.

The 13028HNT, with a hyperbolic primary mirror, produces round and sharp stars within the full-frame format and supports a 44mm imaging circle. Compared with the more widely used focal  ratio of f/4, the 13028HNT can attain the same image brightness with almost half of the exposure time. Additionally, due to its compact and concise design of the telescope tube, it will certainly create huge interest on the market. Users who need a compact, but extremely fast travel telescope would benefit immencely.

365ASTRONOMY TESTING PROCEDURES

We would usually test about 30 - 60% of  the arriving Sharpstar and Askar telescopes (except the smallest ones in the FMA and ACL range). This will provide us with a good understanding of the quality of that batch of optics. We would also test the focuser and check the optical tube, tube rings and dovetail bar and accessories for any visible damage or fault and take a series of test images with a full frame dSLR camera of a specially designed test chart that will show whether the telescope is fit for a full frame sensor or not, whether the image is flat in all corners and generally it will indicate the quility of the optics, i.e. resolution. Whilst we do store this information for all tested telescopes, we don't usually include a printed report, but if you ask, we might be able to send it to you). If we find that the optics are not correctly collimated then we will send them to a specialist to correct it or if the optics cannot be corrected to a good performance then those will be sent back to the manufacturer for replacement, although our experience with Sharpstar and Asker telescopes is quite good, we rarely had to do that. We believe that there is no need to offer complicated optical test reports that would assume a degree in optical sciences from the user to fully understand them.  

The primary mirror is made of a Pyrex-alike glass PZ33. The thermal expansion coefficient is smaller than that of ordinary glass. The dielectric multilayer coating makes the primary mirror obtain a highly reflective surface of 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 coma corrector is a two-part refractive-lens set, one of which is an ED glass, aiming to simplify the optical system while enhancing the aberration correction level.
 
The telescope tube is totally made of high-end carbon fiber material to achieve a lightweight design whilst creating an artistically beautiful instrument. All the component parts are from CNC constructed metals. The pair of tube rings feature pierced design. Although it increased the production cost, but it will certainly offer an extraordinary customer experience because of its lightweight and detail-oriented design concept.

The focuser is a 2.5" rack-and-pinion device. It is 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.

Although the telescope doesn't come with an instruction manual, one of our friends has written a nice tutorial that is available via his website.

Click here for  A STEP BY STEP GUIDE TO COLLIMATION by Simon Todd.  Link shared with his permission.

Technical parameters:

Aperture：130mm

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 Vixen-style dovetail plate）
Resolution：0.89 arc second
Focuser：2.5" with fine-adjustment
Limiting visual magnitude：12.3
Back-focus：55mm

BOX DIMENSIONS/WEIGHT: 38 x 42 x 64 cm, 11.5kg

*Please note, eyepiece is not included.
 

 

 

SAMPLE IMAGES

Click here to see the original image: Orion-Horsehead-Flame Image by Sharpstar 13028HNT

Below image has been heavily reduced in size: appr. 1/3 of the original size.