Hyperstar or Small Refractor

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TimW
Posts: 561
Joined: Wed Oct 18, 2017 1:15 pm

Hyperstar or Small Refractor

Unread post by TimW » Wed Jul 29, 2020 10:45 am

I've got an 8" Celestron SCT scope currently and I'm trying to decide whether to buy a hyperstar or a small refractor for imaging purposes. My SCT is a f 10 with a focal length of 2032mm. FOV is approximately 25 arc sec. The hyperstar will reduce that to an f 1.9 and increase light gathering speed by 25x and increas my FOV to about 4.1 degrees at a cost of about $1000.

My other option is to find a small refractor. I don't know what size I should get and I was hoping that this bunch of really smart people could help me out in deciding which is the best route to take.
Tim W.

Laurie J. Wood
March 22, 1967 - August 23, 2019
Forever in my memory. Forever in my heart.

Scope: 8" Celestron SCT on an AVX equatorial mount
Solar Scope: Lunt Solar System 60 mm Double-Stacked H-Alpha
Imaging Camera: ZWO ASI1600MC-Cool
Autoguide: PHD2
Image Capturing: SharpCap
DebayerIng: PIPP
Planetary Stacking: Autostakkert
Planetary Post Processing: Registax
Deep Sky Stacking: Deep Sky Stacker
Deep Sky Post Processing: Photoshop
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Pete
Astro Day Coordinator
Posts: 3192
Joined: Fri Jun 13, 2003 9:03 pm

Re: Hyperstar or Small Refractor

Unread post by Pete » Wed Jul 29, 2020 1:55 pm

Hi Tim,

I've a Hyperstar that was used only briefly as I moved from imaging into astrometry. An early note from my observing log of 30 Jan 08:

"This afternoon I further modified the 14” so that I can now change out the Hyperstar system and run in standard SCT configuration. I continue to be impressed with the quality of the parts Starizona is turning out. As promised, Dean aligned the secondary alignment mark with the offset mounting screw hole so that the secondary’s mark aligns with the mark where the corrector plate aligns with the tube (and primary) It’s now easier to put the Hyperstar on than it is to set up a focal reducer."

Used it for just a few months. It was easy to switch out and at the reduced focal length the stars were sharp on my old Meade DSI 2C. No explaination as to why use was discontinued. Perhaps because I was exploring astrometry and the MPC specifically banned the use of Hyperstar.

Not sure that this is helpful :shock:
Pete P.
TimW
Posts: 561
Joined: Wed Oct 18, 2017 1:15 pm

Re: Hyperstar or Small Refractor

Unread post by TimW » Wed Jul 29, 2020 2:24 pm

The only potential drawback I can see would be an asymmetrical diffraction pattern on stars due to camera and associated cabling. Do you see this when using your hyperstar?
Tim W.

Laurie J. Wood
March 22, 1967 - August 23, 2019
Forever in my memory. Forever in my heart.

Scope: 8" Celestron SCT on an AVX equatorial mount
Solar Scope: Lunt Solar System 60 mm Double-Stacked H-Alpha
Imaging Camera: ZWO ASI1600MC-Cool
Autoguide: PHD2
Image Capturing: SharpCap
DebayerIng: PIPP
Planetary Stacking: Autostakkert
Planetary Post Processing: Registax
Deep Sky Stacking: Deep Sky Stacker
Deep Sky Post Processing: Photoshop
User avatar
Pete
Astro Day Coordinator
Posts: 3192
Joined: Fri Jun 13, 2003 9:03 pm

Re: Hyperstar or Small Refractor

Unread post by Pete » Wed Jul 29, 2020 2:53 pm

Sorry Tim, but I don't recall. Remember being concerned that the old DSI was non-symmetrical and the USB cable was across the aperture. My memory is quite fallible but don't recall that it was a problem.
Pete P.
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