Sharpstar 150 F2.8 HNT astrograph

[CCD-Freak]

My finger is hovering over the BUY button for this very cool looking little astrograph.  The siren song of imaging at F2.8 is calling me.  

Does anyone have any experience with this instrument?

John
CCD-Freak
WD5IKX

[tooth_dr]

@Davey-T lol 

[CCD-Freak]

The little devil on my shoulder is saying..."Push the button...just buy the bloody thing !!!!"  LOL

 

John
CCD-Freak
WD5IKX

Edited September 6, 2020 by CCD-Freak

[MarkAR]

Go for it, then write a review.

[johninderby]

Davey-Ts thread.

 

Edited September 6, 2020 by johninderby

[tooth_dr]

 

[Davey-T]

39 minutes ago, CCD-Freak said:

My finger is hovering over the BUY button for this very cool looking little astrograph.  The siren song of imaging at F2.8 is calling me.  

Does anyone have any experience with this instrument?

Read the thread on Cloudy Nights, that might put you off 

Dave

[CCD-Freak]

Good info...I will read that thread.  I am not afraid of collimating the scope.  I have an 8" F3.8 Newt so I have learned to do it so that does not scare me too much.  If the correction is good and the scope holds collimation well I may "Push the button".

 

John
CCD-Freak
WD5IKX

[Davey-T]

1 minute ago, CCD-Freak said:

I am not afraid of collimating the scope.

Tricky collimating something when the mirror flops up and down 😂

OTOH if you get one from TS they claim to test them before sending but don't know how far they go though, mine needed rebuilding from the ground up.

Dave

[melsmore]

There's a Test Report by Alan Dyer of it in September 2020 Sky and Telescope too.  (Page 68).

[CCD-Freak]

4 hours ago, melsmore said:

There's a Test Report by Alan Dyer of it in September 2020 Sky and Telescope too.  (Page 68).

Alan's review in S&T is what got me interested in the SS15028HNT to start with.  I just got an e-mail from Alan and he indicated he enjoyed testing it and did not have any serious issues with it.

My finger is quivering !!! 

 

John
CCD-Freak
WD5IKX

[Davey-T]

50 minutes ago, CCD-Freak said:

My finger is quivering

Read the Cloudy Nights thread first.

Dave

[CCD-Freak]

I have read the CN thread several times.  Only a few have had issues and they were attempting to use full frame and heavy cameras.  Most of the other posters were having good results.  The SharpStar Facebook page is full of great images made with the 15028HNT.  The thread is over a year old and I hope SS has worked out some of the early production issues.  I have not pushed the button yet and I am still looking for input.   Your thread here does cause concern.  I hope those problems have been fixed in later production.

 

John Love
CCD-Freak
WD5IKX

Edited September 7, 2020 by CCD-Freak

[gorann]

Hold your finger! Here is another thread you should read - apparently the Sharpstar optics are far from sharp but quite fuzzy (bad spot diagram) compared to the competitors, when it comes to astrographs they are Tak Epsilon and Celestron RASA.

https://www.dpreview.com/forums/post/63734509

For the same price you get a RASA 8 f/2 with much bigger aperture (collects twice as much light), better spot diagram, and no collimation issues, at least not for me. I got one for this season and I am very happy with it so far. You can read some of my recent threads:

PS. With the RASA 8 you cannot use a DSLR but need a dedicated circular astrocamera (like an ASI) - I don't know what camera you have or what your plans are.

Edited September 7, 2020 by gorann

[gorann]

Found these spot diagrams for the Sharpstar 150 Hypergraph (from the Teleskope Service site - bottom image) and RASA 8 (top image from a Celestron booklet, file attached as pdf). Note that the one for Sharpstar is on a 100 µm scale and that the one for RASA 8 is on an 18 µm Scale, so its seems to me that the RASA is about 5-times sharper. Make sense that Sharpstar chose to present the spots at a 100 µm scale. However, I am no expert on spot diagrams so maybe I am missinterpreting them.

RASA-booklet-8in-11in-36cm-pdf.pdf

Edited September 7, 2020 by gorann

[tooth_dr]

Whilst checking the spot diagrams for the Epsilon I came across this: a new epsilon e160ed is being released 😮

https://www.takahashiamerica.com/blogs/product-announcements/takahashi-announces-the-epsilon-e-160ed-reflector/

[gorann]

14 minutes ago, tooth_dr said:

Whilst checking the spot diagrams for the Epsilon I came across this: a new epsilon e160ed is being released 😮

https://www.takahashiamerica.com/blogs/product-announcements/takahashi-announces-the-epsilon-e-160ed-reflector/

630 dollars for the tube rings! I find no scale on the spot diagrams. Can you interpret them?

Tak has published these spot diagrams for the Epsilon 180 on a 50 µm scale (side length of the squares) and it suggests a similar spot  size to the RASA

Edited September 7, 2020 by gorann

[CCD-Freak]

More "mud in the water".......When you overlay all the wavelengths and adjust for the difference of the block size there is not much difference in the spot size.

I would love to have the new Tak E-160ED it more than two times more than the 15028HNT.  And I am not a fan of the Hyper Star 8 and RASA 8 so that is why I am interested in the SS. 

Is the slight difference in the spot diagram going to show up when one factors in typical seeing?   More research to do. 

 

John Love
CCD-Freak
WD5IKX

Edited September 7, 2020 by CCD-Freak

[gorann]

I dont think you could compare the RASA to the Starizona hyperstar add-on which just  seems to be a lot of trouble.

[CCD-Freak]

I agree the RASA is better than the Hyperstar but I don't care for either.  I don't like the camera in front of the corrector with the cable diffraction issues and heat from the camera cooler billowing through the field of view.   I might decide to live with the RASA 8 since it is a bit faster and costs less.   I like the diminutive size of the 15028HNT so it is a tough decision.

John Love
CCD-Freak
WD5IKX

[Davey-T]

Another point about the 150HNT 2.8 is it's a PITA to balance just resorted to purchasing a Rainbow mount for it with no balancing required.

Dave

[CCD-Freak]

Balance won't be a problem with my AP900 mount which will dwarf the 15028HNT should I decide to get it.  The picture shows my 8" F3.8 imaging Newt.  It will also carry the RASA 8 should I decide to go that way.

John Love
CCD-Freak
WD5IKX

[gorann]

8 hours ago, CCD-Freak said:

I agree the RASA is better than the Hyperstar but I don't care for either.  I don't like the camera in front of the corrector with the cable diffraction issues and heat from the camera cooler billowing through the field of view.   I might decide to live with the RASA 8 since it is a bit faster and costs less.   I like the diminutive size of the 15028HNT so it is a tough decision.

John Love
CCD-Freak
WD5IKX

Cable diffracton spikes can be easily overcome by organizing the cables in a circle. Since I did that I cannot see any spikes. I had not heard that heat from the camera would be an issue. Maybe the fan in the camera will create enough airflow to avoid this. I rather see the camera heat as an advantage since I do not need a heater band to protect agains dew on the corrector plate (I certainly need that on my SCTs). The camera heat, in combination with a dew shield does a good job of keeping the dew away.

 

[tooth_dr]

8 minutes ago, gorann said:

Cable diffracton spikes can be easily overcome by organizing the cables in a circle. Since I did that I cannot see any spikes. I had not heard that heat from the camera would be an issue. Maybe the fan in the camera will create enough airflow to avoid this. I rather see the camera heat as an advantage since I do not need a heater band to protect agains dew on the corrector plate (I certainly need that on my SCTs). The camera heat, in combination with a dew shield does a good job of keeping the dew away.

 

Ah, so how do you use a FW and mono camera?

[gorann]

22 minutes ago, tooth_dr said:

Ah, so how do you use a FW and mono camera?

You need the Baader UFC Universal Filter Changer System made for the RASA - FW is not possible.

https://www.firstlightoptics.com/baader-filters/baader-ufc-universal-filter-changer-system.html

Edited September 8, 2020 by gorann