Evaluating Sharpstar 15028HNT purchase - can someone share some data? - Forums

Topic starter

Oct 20, 2023

Hi,

I am looking to buy a telescope. Preferably fast telescope. I’ve been eying the sharpstar FRA telescopes which are F3.9 when used with reducer.
Sharpstar 15028HNT looks equally interesting. I found some good images in astrobin. I’d like to take a deeper look into how the data looks like.
Can someone share a calibrated master light frame taken with this telescope?

(I have sample single subs already, looking only for integrated file)

I appreciate your help.

Thanks,
Deepan

José María Moreno Santiago

Oct 20, 2023 · Edited: Oct 20, 2023

Hola, buenos días.
Yo he usado el SharpStar 15028HNT, es un tubo muy bueno aunque algo delicado para colimar. Su apertura f/2,8 proporciona una profundidad de campo muy pequeña por lo que necesita programar autofoco a menudo cada pocos subframes. Por lo demás, una vez ajustado con paciencia, es una experiencia deliciosa. No es un telescopio de iniciación pero usado con calma le proporcionará muchas satisfacciones. Esta foto está hecha con él: https://www.astrobin.com/vr3w64/

Well Written Concise

Laurent Gatte

Oct 20, 2023

Hello Deepan,
I had one during 1 year, great scope, very fast, very nice but I decided to sell it because of the followings:
- collimation unstable and tricky (in nomad)
- balancing is complicated in particular if you put the cam toward the ground
- from aps-c sensor size, tilt is a nightmare to maintain
- there is always a corner not well corrected (in aps-c configuration)
- it is very sensitive to transversal light and fog
- ….
On the paper, it sounds like a very good idea but in practical, it is difficult to manage very nice images in particular if you are (like me) very demanding in stars quality in the corner of the sensor. Have a look on my astrobin I kept he best I did (North america) with this scope and zoom the stars you will see what I mean.
I switched to a FSQ 106 and my life is really simpler and better.
Laurent

Helpful

Daniel Carter

IOTD Staff

Oct 20, 2023

The Epsilon and HNT scopes are really nice scopes. However, collimation is a pain and tilt has to be addressed even with an APS-C sensor. It is definitely doable. I have a full frame camera on an Epsilon 160ED at a remote site in New Mexico. I use an ASG Photon cage to finely adjust back focus and tilt. It is absolutely needed since the critical focus zone is so narrow (think microns). I haven't used the Sharpstar scope but collimation on the Epsilon is tricky but it isn't horrible once you get the process down. They are both the same type of Newtonian scope.

I have an Askar FRA300 I use for travel. It is much easier to use since it is a refractor and collimation isn't needed. Tilt can still be an issue but it isn't as crucial as the faster Newts. If you are first starting out in Astrophotography I highly recommend going the refractor route. Another option besides the FRA line is the PHQ line of refractors.

Example shot from the Epsilon (tilt and back focus has been finely tuned): https://www.astrobin.com/86smv8/

Example shot from the FRA300 (not tilt has been adjusted): https://www.astrobin.com/da1rs1/

Helpful

Hartmuth Kintzel

IOTD Staff

Oct 20, 2023 · Edited: Oct 20, 2023

Hi Deepan,

about a year ago I bought the Sharpstar 15028HNT.
Since the primary mirror was a bit loose, it was fixed with felt strips.
Since then it is very stable and the adjustment remains intact even when transported in the car.
I didn't have any major collimation problems with my ASI1600MM camera.
Probably because my ASI1600 has a relatively precise built in chip. (Which is not the case with every ASI1600.)
Last spring I bought an Omegon veTEC 571C, which has an APS-C chip that is installed not so precisely.
This means that I have significantly more difficulty with the stars in the corners. The camera has a tilt adapter. Nevertheless, collimation is very tricky.

Please refer:

Sharpstar with ASI1600MM:
https://www.astrobin.com/nbsdn4

Sharpstar with Omegon veTEC 571C:
https://www.astrobin.com/d8hus2/0/

CS
Hartmuth

Helpful Concise

Georg N. Nyman

Oct 20, 2023

I own it, use it with an APS and a full frame mono camera - optics is very fine, collimation pretty tricky, once done and treated well - stable. Would be again my first choice.

Blaine Gibby

Oct 20, 2023

I bought one and ended up sending it back. I was very much interested in the fast optics but as others have mentioned, collimation is tricky (it was a nightmare). I could never get the tilt out of the focuser and the mechanism for rotating the camera angle is easily the Achilles heel.

Well Written Concise

Tommy Blomqvist

Oct 20, 2023

There are some images on Astrobin but even if I haven't owned one some astrofriends of mine have.
f/2,8 is really fast and that shows on the complexity on getting this OTA working the way you want.
I've been with them (the friends) when I'm using f/5 and f/4 Newtonians and by the time I hade captured a good night they still struggled with collimation.

Deepan Vishal

Topic starter

Oct 24, 2023

I appreciate everyone’s input here. I was able to look at some pictures. I am convinced that I don’t have the skills and meticulousness to handle this lovely scope. I’ll miss the 150mm aperture!

I will be sticking to the refractors, which I am already comfortable using.

It will be sharpstar 94 at F4.4, FRA400 at F3.9 and SVX102- Raptor at F5.6.

I will be purchasing one or two of these scopes and retain the better performer.

Again thanks everyone for their valuable feedback & suggestions

Well Written Respectful

Deepan Vishal

Topic starter

Nov 2, 2023

Hello again everyone,

I purchased both, the Sharpstar 94EDPH and Sharpstar HNT15028.

From my initial results, I am happy with what both the telescopes produced.
The telescopes were around 410 and 420 FL, so the FOV was similar.
However, HNT15028 produced slightly better SNR.

Though 94EDPH is good, I've decided to keep the HNT15028 and tame it.
How do you guys deal with dew? What hind of dew heaters do you use.

Thanks,
Deepan

andrea tasselli

Frequent contributor

Nov 2, 2023

Deepan Vishal:
How do you guys deal with dew? What hind of dew heaters do you use.

Since we're talking newts here, by and large, the answer is you don't deal with it. Get a long dew shield and cross your fingers. On the bright side, I only had situations when the secondary was totally fogged up just a handful of times in more than 20 years in the hobby.

Deepan Vishal

Topic starter

Nov 3, 2023

Thanks for the information Andrea. This is my second attempt to image with Newtonians.
My previous attempts failed massively that I never made it to stages where I though about dew.

andrea tasselli:
Deepan Vishal:
How do you guys deal with dew? What hind of dew heaters do you use.

Since we're talking newts here, by and large, the answer is you don't deal with it. Get a long dew shield and cross your fingers. On the bright side, I only had situations when the secondary was totally fogged up just a handful of times in more than 20 years in the hobby.

Christian Großmann

Nov 4, 2023

I use a Dew shield for both of my Newtons. I also put on DIY heaters on both of the mirrors. For the primary I used heat wire I wrapped around it and mounted it with aluminium foil that has glue on it. Behind the secondary, I used 3 resistors which can handle some Watts and send some current through it. But the point is, that I used the wrong connectors to plug them into my power supplies on the scopes. At one point I realized, that both of them never really worked until I changed the plugs. So the moral of the story is, that I was concerned about the dew, but with the dew shields itself, I never had issues with dew. At least, I can't remember issues.

So, depending on the climate you have at your place, there may be no issues with dew shields alone at all. I live in germany, so our climate is somewhat average (if there is something like average climate).