Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

HyperStar and FunStar?

  • Please log in to reply
4 replies to this topic

#1 Rac19

Rac19

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,837
  • Joined: 05 Aug 2016

Posted 09 August 2020 - 05:29 AM

I have HyperStar so I am familiar with that but the FunStar intrigues me. There's very little technical info but from some of the images, there appears to be no glass , it appears to be just a camera mount for the corrector plate. 

 

Is this correct? If so how does it compare with the HyperStar? They both say that they produce a focal ratio of f/2.

 

Just curious.



#2 Tapio

Tapio

    Gemini

  • -----
  • Posts: 3,124
  • Joined: 24 Sep 2006
  • Loc: Tampere, Finland

Posted 09 August 2020 - 06:01 AM

There are numerous threads of FunStar here in CN.
But in principal it's a poor man's Hyperstar.
So you gain nothing compared to Hyperstar and the quality is low.

#3 Rac19

Rac19

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,837
  • Joined: 05 Aug 2016

Posted 09 August 2020 - 04:41 PM

There are numerous threads of FunStar here in CN.
But in principal it's a poor man's Hyperstar.
So you gain nothing compared to Hyperstar and the quality is low.

I agree that it's so much cheaper that you would not expect to perform as well as HyperStar. Having already purchased the latter, I have no reason to consider purchasing FunStar. I am curious though as whether or not it has a lens. I can't see one in any of the images that I can find.



#4 jprideaux

jprideaux

    Ranger 4

  • -----
  • Posts: 320
  • Joined: 06 May 2018
  • Loc: Richmond, VA

Posted 09 August 2020 - 05:12 PM

It is correct that the funstar has no lens.  Imagine a hyperstar with all lens(s) taken out.  That is the funstar and why the funstar is so inexpensive.  All it does is let you mount your camera at the native focal plane of the primary mirror of the SCT which has an F2 mirror.  But the resulting image will have lots of uncorrected aberrations.  The purpose of the lens(s) in the hyperstar is to correct for these aberrations.  You could have fun, though, in looking at some targets (like fuzzy blobs) that don't look that different with the aberrations.  Imagers would not be happy, though, with the results.  If you already have the hyperstar, you have no need to get the funstar.  If you can't afford the hyperstar, the funstar could be an option if you accept that the image quality will be poor.


  • Rac19 likes this

#5 Rac19

Rac19

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,837
  • Joined: 05 Aug 2016

Posted 09 August 2020 - 05:43 PM

It is correct that the funstar has no lens.  Imagine a hyperstar with all lens(s) taken out.  That is the funstar and why the funstar is so inexpensive.  All it does is let you mount your camera at the native focal plane of the primary mirror of the SCT which has an F2 mirror.  But the resulting image will have lots of uncorrected aberrations.  The purpose of the lens(s) in the hyperstar is to correct for these aberrations.  You could have fun, though, in looking at some targets (like fuzzy blobs) that don't look that different with the aberrations.  Imagers would not be happy, though, with the results.  If you already have the hyperstar, you have no need to get the funstar.  If you can't afford the hyperstar, the funstar could be an option if you accept that the image quality will be poor.

Thanks, a very comprehensive reply. It's interesting that there is more to lens design than just achieving a focal point. The corrector plate on SCTs is an example as were the corrective elements added to the Hubble telescope to fix a manufacturing error. 




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics