SharpStar 15028HNT

After months of trying to get my trusty Sky-Watcher Quattro F4 to work with the ASA 0.73x reducer I decided to go all in on an F2.8 astrograph. After doing some research I stumbled across the SharpStar 15028HNT F2.8 Hyperboloid Newtonian Reflector from my local supplier 365Astronomy.

After toying with the idea and speaking to my good friend Nick from Altair Astro and with the idea of going back to a refractor, I decided that I could not go back to slower than F4 and I wanted something that in essence would work with a bigger sensor than my QHY183M, and the Sharpstar looked like it could work for me, so I placed my order with Zoltan from 365Astronomy and collected it the following day.

Unboxing the scope, I was like a young child at christmas, the scope came with a very sturdy protective hard case and removing the scope out of the case you could immediately feel that a lot of time and effort had gone into producing the 15028HNT.

Aperture: 150mm
Focal Length: 420mm
Focal Ratio: F2.8
Weight: 6kg
Tube Material: Carbon Fiber

With the scope unboxed I started to fit my equipment onto the scope. In order to fit my Sesto Senso I had to rotate the focuser 90 degrees clockwise due to the telescope mounting rings, this is when I noticed an isue that one of the grub screws on the focuser would not tighten and I needed to stop the backlash, fortunately there’s another grub screw on the other side that tightened and stopped the backlash.

Before I attached my imaging equipment, I had to ensure that the telescope was collimated, so I stumbled across the collimation guide which after speaking with my good friend Terry Hancock over at Grand Mesa Observatory who was also evaluating the same scope, we both agreed that the colimation guide wasn’t very well written as it mentioned nothing about collimating the primary. One thing that it mentioned is to remove the corrector, Sharpstar include a tool for you to remove the mounting plate and corrector, but here is a word of advice……..remove this when the telescope is cold, take that advice from someone who tried to remove it whilst it was warm!

I performed a laser collimation with my Concenter Eyepiece to check the secondary, and then a laser to check the primary, now the collimation guide says to remove the corrector, I have done validation with both the corrector removed and the corrector in place, and it made no difference whatsoever, so my opinion is to leave the corrector in place.

With the scope closely collimated, I mounted my StarlightXpress Filterwheel and Camera which with the 15028HNT is an M48 thread for the gear to screw onto.

I will post some images as soon as I have completed some, the weather has been pretty poor (probably because I bought a new scope), but the frames I have got so far are very sharp, pinpoint and I can honestly say I have never seen images come directly off the camera so sharp.

My field of view with the QHY183M is around 1.21 Arcsec/Pixel which gives me a FOV or around 1.81°x1.2° and I love the difraction spikes being at 45 degrees compared to the 90 degrees on the skywatcher and I already have a pretty full target list for this scope ready to go this season.

Apart from the couple of product issues I have experienced (Grub screw on focuser and tube clamp thumbscrew being threaded) I am extremely happy with the scope, it is performing really well and here are a couple of work in progress images that I have started

Dark Shark Nebula Moscaic Panel 1 – 51x300S in Red, 25x300S in Green and Blue
Elephant’s Trunk – 51x300S in 6nm Ha
M45 – Mosaic Panel 1 – 12x150S in R, G and B

After a few weeks, the telescope has held collimation very well, I have not had to perform any re-collimation, I will re-evaluate this in the much colder months of winter.

I am so happy with the scope that I am actually considering a second one for an OSC Camera with a bigger sensor.

4 thoughts on “SharpStar 15028HNT”

  1. Hello Simon,

    My name is Lior Spiegel and I`m from Israel.
    I do Astrophotography and I`m looking to buy a new Astrograph.
    I`m showing interest of the Sharpstar 150 F/2.8, saw that you have it, I do have couple of questions:
    I do own the same CCD camera and FW as yours, the only difference is that I use an OAG and you use a guide scope, the manufacturer specified the back focus to be 55mm but with my OAG I reach 60mm, I wish not to uninstall the OAG so will need another solution, can you help me with that?
    Just to let you know, Terry Hancock is a friend of mine as well, he recommended you to remove the corrector prior to collimation, can you explain to me how to do that? I`m using a Glatter 2″ collimator.
    I can see that you are using Pegasus control box, are satisfied with it? I`m planning to buy the expensive one.
    Generally, do you like the performance of this scope? what are the drawback of this scope? Does it hold collimation well during a night session?

    Thanks a lot and clear skies,

    Lior

    1. Hi Lior
      I did not use an OAG with this because of the limited back focus, especially as you have to factor in a filterwheel too, you may be able to get away with a TS9OAG perhaps, but yes the back focus is pretty spot on for 55mm. I am moving to an APS-C sized OSC now, so I will be using an OAG again.

      I am very happy with the Pegasus Astro USB HUB, it works flawlessley for me, I have even made some suggestions to Pegasus Astro that have been implemented into their software.

      I have not had to re-collimate the scope across a whole season, it has held collimation very well, I love the performance and how razor sharp the images are that come off the sensor without any sharpening. In all my images I have done tiwh the 15028HNT I have not had to do any sharepening whatsoever

  2. Hi there Simon,

    I also own a SharpStar 15028HNT that I use with my ASI183MM. I really appreciate your review and collimation guide!
    In your collimation guide, it looks like you have a dew heater on your secondary mirror. Would you mind telling me which brand this is or if you made it? I really suffer from dew forming on my secondary, it would be very much appreciated!

    Thanks,
    Stefan

    1. Hi Stefan
      Yes I use a secondary heater which I got from 365astronomy.com I also cut out a hole in the plate behind the primary and fitted a 90mm fan which also prevents dew forming on the primary with it being such a short tube
      Simon

Leave a Reply

Your email address will not be published. Required fields are marked *