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

Older Celestron Diagonal Reflectivity?

  • Please log in to reply
2 replies to this topic

#1 PJBilotta

PJBilotta

    Lift Off

  • *****
  • topic starter
  • Posts: 8
  • Joined: 02 Sep 2017
  • Loc: Portland, Oregon

Posted 25 March 2019 - 03:40 PM

Hi, all. I'm considering a diagonal upgrade from a 2" Celestron #93215. Celeston's materials never listed a reflectivity for this diagonal - merely "high reflectivity" and fully multicoated (not XLT. Does anyone know the approximate reflectivity of these non-XLT diags.

 

I'm curious whether an upgrade to a dielectric or XLT would make a significantly noticable difference for purely visual observation.

 

Thanks for any info you can provide.



#2 photoracer18

photoracer18

    Vanguard

  • *****
  • Posts: 2336
  • Joined: 02 Sep 2013
  • Loc: Martinsburg, WV

Posted 25 March 2019 - 04:34 PM

Regular reflectivity was around 89% at one time. It might be a few percentage points higher these days but not near 99% dielectric coatings. A 10% difference is right on the edge of whether the human eye can see a real difference. But on that note there are lots of cheaper alternatives these days to the Maxbright and Everbright diagonals that used to be the only thing out there.

#3 jjack's

jjack's

    Messenger

  • -----
  • Posts: 457
  • Joined: 01 Apr 2012
  • Loc: normandy

Posted 26 March 2019 - 02:04 AM

XLT or not, these enhanced diagonals have 95 to 97 % reflectivity. They also are more efficient than dielectrics in the deep red part of the spectrum. Aluminum reflectivity fall down over the years, but multicoatings protect the aluminum layer so dont worry. Keep it and enjoy smile.gif




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