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

GSO 8"f/12 Cassagrain

  • Please log in to reply
13 replies to this topic

#1 Nippon

Nippon

    Soyuz

  • *****
  • topic starter
  • Posts: 3,700
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 11 January 2020 - 10:36 AM

How would the GSO 8" f/12 Cassegrain fair against a Celestron Edge 8 HD or a Mewlon 210. I would think it would boil down to if the GSO mirrors have a very good figure. 



#2 carolinaskies

carolinaskies

    Vanguard

  • *****
  • Posts: 2,260
  • Joined: 12 Dec 2014
  • Loc: Greenville SC

Posted 11 January 2020 - 10:47 AM

GSO scopes are shelf-line products meaning you could get very good, good, mediocre on any shelf unit ordered online.  

Classical means it's secondary is held by a spider, so you'll get diffraction spikes.  

F/12 means longer exposures for the same aperture 

Be aware some of these scopes may have the focuser and primary mirror cell integrated rather than seperated.  If it isn't that's good, if it is, then heavy imaging setups may cause unwanted flexure and change to collimation. 

Check out Astrobin.com and seek out the various OTAs for comparing possible results.  

If you're doing planetary imaging the GSO will be a good performer with the longer focal length and no worry about imaging times.  And having the external focuser gives it an advantage over the Edge/Mewlon in this category. 



#3 Nippon

Nippon

    Soyuz

  • *****
  • topic starter
  • Posts: 3,700
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 11 January 2020 - 10:59 AM

Should have mentioned I'm visual only and that will never change. I know about the spider and it's effects. 



#4 calypsob

calypsob

    Fly Me to the Moon

  • *****
  • Posts: 5,719
  • Joined: 20 Apr 2013
  • Loc: Virginia

Posted 11 January 2020 - 11:30 AM

The view in my old GSO RC 8 were extremely sharp.  Having no glass imo gives a very sharp image and cooling is alot faster than a c8


  • Stephen Kennedy likes this

#5 eros312

eros312

    Viking 1

  • *****
  • Posts: 703
  • Joined: 14 Feb 2009
  • Loc: Tampa, FL

Posted 11 January 2020 - 11:37 AM

I just bought one while they were on sale. No dew problems was a big deal for me, I live in Florida. It's about 5 pounds heavier than a 8 inch SCT.


  • Nippon, Terra Nova and Stephen Kennedy like this

#6 Nippon

Nippon

    Soyuz

  • *****
  • topic starter
  • Posts: 3,700
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 11 January 2020 - 11:48 AM

I just bought one while they were on sale. No dew problems was a big deal for me, I live in Florida. It's about 5 pounds heavier than a 8 inch SCT.

I'm there with you about the dew I live about 60 miles away in Winter Haven. I use dew heaters on my 4" refractor and my 8" SCT which solves the problem but they need a lot of power. At home and at Chiefland where I sometimes go there is AC and I just use a converter. How do you like the optical performance?



#7 eros312

eros312

    Viking 1

  • *****
  • Posts: 703
  • Joined: 14 Feb 2009
  • Loc: Tampa, FL

Posted 11 January 2020 - 11:52 AM

I'm waiting for my new Ioptron GEM45 to arrive. Haven't used it yet. 



#8 Nippon

Nippon

    Soyuz

  • *****
  • topic starter
  • Posts: 3,700
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 11 January 2020 - 12:03 PM

I'm waiting for my new Ioptron GEM45 to arrive. Haven't used it yet. 

I'll check back with you if you don't mind.


  • eros312 likes this

#9 coopman

coopman

    Fly Me to the Moon

  • *****
  • Posts: 6,530
  • Joined: 23 Apr 2006
  • Loc: South Louisiana

Posted 11 January 2020 - 12:52 PM

Have you seen Larry Carlino's review at Astromart?


  • Tyson M likes this

#10 Tyson M

Tyson M

    Aurora

  • *****
  • Posts: 4,831
  • Joined: 22 Jan 2015
  • Loc: Canada

Posted 11 January 2020 - 04:53 PM

Have you seen Larry Carlino's review at Astromart?

I was going to mention the same thing.  The 8" SCT will be brighter as the GSO 8" is not operating at full aperture.

 

IMO, the only reason to choose it over a 180 mak cass is if you have extreme dew problems. 



#11 cildastun

cildastun

    Vostok 1

  • -----
  • Posts: 180
  • Joined: 08 Aug 2012
  • Loc: Oxford, UK

Posted 12 January 2020 - 02:37 AM

 

 

IMO, the only reason to choose it over a 180 mak cass is if you have extreme dew problems. 

My personal experience is that insulating my 180 Mak has cured the dew issue (it was not that bad anyway) and to some of us, having a closed tube scope is advantageous as I live in a site surrounded on three sides by farmland with big airborne dust issues for much of the year. 

 

Chris


Edited by cildastun, 12 January 2020 - 03:49 AM.


#12 Nippon

Nippon

    Soyuz

  • *****
  • topic starter
  • Posts: 3,700
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 12 January 2020 - 09:18 AM

I don't have an Astromart account. I've tried but it keeps saying my email is already in use I don't remember my password and have never been able to get things straightened out. I've given up on them. Besides don't they charge a fee? That aside if the effective aperture is not 8" for the GSO what is it's true aperture?



#13 eros312

eros312

    Viking 1

  • *****
  • Posts: 703
  • Joined: 14 Feb 2009
  • Loc: Tampa, FL

Posted 12 January 2020 - 10:32 AM

The same review is posted here on Cloudy Nights https://www.cloudyni...assegrain-r3215



#14 Tyson M

Tyson M

    Aurora

  • *****
  • Posts: 4,831
  • Joined: 22 Jan 2015
  • Loc: Canada

Posted 12 January 2020 - 01:36 PM

My personal experience is that insulating my 180 Mak has cured the dew issue (it was not that bad anyway) and to some of us, having a closed tube scope is advantageous as I live in a site surrounded on three sides by farmland with big airborne dust issues for much of the year. 

 

Chris

I found that insulating my mak did the same thing.  My guess is it really delayed the front menicus reaching dew point temperature as fast. 




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