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

Coma corrector for Binotron?

  • Please log in to reply
2 replies to this topic

#1 bokemon

bokemon

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,547
  • Joined: 28 Jul 2020
  • Loc: Silicon Valley, California

Posted 26 February 2025 - 09:17 PM

Hello folks, 

I have a Denk Binotron 27 system with power switch and OCS.  It works very well in refractors, but not so hot in a Newtonian.  The stars are larger than when using a regular eyepiece + coma corrector, and of course stars near the edge are even worse.  I mainly use it in low power mode for viewing clusters, but sometimes switch to medium power, or high power for planets and doubles.

I see there's an APM coma-correcting telecentric 1.5x barlow, and also a 1.7x Baader version.  However, I'm not sure how well they'll work with the power switch, which is effectively changing the back-focus a lot from the more standard 100-and-something path length of typical binoviewers.

I've also read comments that for low power, you'd be better off using a linear binoviewer + standard coma corrector.

My newtonians are F/4 and F/5.  At some point, there may even be an F/3.5.


  • Shubham likes this

#2 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 29,813
  • Joined: 01 Feb 2006

Posted 28 February 2025 - 10:12 AM

The Baader 1.7x Coma Corrector worked well for me at f/5, but I don't know about with faster scopes.

 

These were not avialable for some long period of time, and may be out of production. 



#3 bokemon

bokemon

    Surveyor 1

  • *****
  • topic starter
  • Posts: 1,547
  • Joined: 28 Jul 2020
  • Loc: Silicon Valley, California

Posted 05 March 2025 - 07:39 AM

Agena astro has one right now.

Edit - oops, saw that there were many threads on this via google search

Edit 2 - never mind, bought linear binoviewers instead


Edited by bokemon, 05 March 2025 - 08:35 AM.



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