Jump to content


Photo

60mm f/20... 80mm f15 comparo

  • Please log in to reply
8 replies to this topic

#1 Bonco

Bonco

    Gemini

  • *****
  • Posts: 3450
  • Joined: 17 Apr 2006
  • Loc: Florida

Posted 17 March 2012 - 03:54 PM

Been wanting to do a comparo for a long time. Last night clouds moved in so I only had 2 targets for the comparo. Stopped down my Carton 80mm f/15 to become a 60mm f/20.

Rigel absolutely beautiful APO type view at 60mm, f/20, However I found the view more pleasing unmasked at 80mm mainly because the secondary was noticably brighter.

Alnitak surprised me, the 60mm with a 9mm eyepiece showed a crisp split when skies steadied. I've never had this good of a view with any 60mm scope. Using the same eyepiece at 80mm the view wasn't as good or sharp... So I cheated and used my 4.8mm Nagler and now the 80mm won. I learned that 60mm f/20's have amazing abilities. I'm sure owners would agree. Cheers, Bill

#2 Larry Geary

Larry Geary

    Surveyor 1

  • *****
  • Posts: 1839
  • Joined: 24 Sep 2006

Posted 17 March 2012 - 06:15 PM

So which scope are you going to keep? :grin:

#3 Bonco

Bonco

    Gemini

  • *****
  • Posts: 3450
  • Joined: 17 Apr 2006
  • Loc: Florida

Posted 17 March 2012 - 06:39 PM

It's only one scope...So I guess I'll keep it. Takes me about 10 seconds to install or remove the 60mm mask.
Bill

#4 dbledsoe

dbledsoe

    Apollo

  • *****
  • Posts: 1003
  • Joined: 09 Jun 2006
  • Loc: Boise, Idaho USA

Posted 17 March 2012 - 06:55 PM

Bill,

Thanks for posting your comparison. That was an excellent idea and I think I'll do the same type of comparison using my new to me Tasco 10K (80mm f/15) if I ever get a clear night. :bawling:

Don

#5 strdst

strdst

    Soyuz

  • *****
  • Posts: 3948
  • Joined: 23 Mar 2008
  • Loc: Oregon Territory

Posted 17 March 2012 - 09:14 PM

Hi Bill,

Stopped down to 60mm this 80mm f/20 would become uh, f/26.6. Would
there be an advantage to that or is f/20 ideally refractor sloooow?

other keith

Attached Files



#6 Bonco

Bonco

    Gemini

  • *****
  • Posts: 3450
  • Joined: 17 Apr 2006
  • Loc: Florida

Posted 18 March 2012 - 04:23 PM

Could be fun to do a comparo, but an 80mm at f/20 should be an excellent optic, free of CA. I doubt stopping it down would improve things except maybe better high power views in unsteady skies. Great looking if not unusual setup. How is the collimation?
Bill

#7 Ain Soph Aur

Ain Soph Aur

    Viking 1

  • *****
  • Posts: 713
  • Joined: 10 Aug 2011
  • Loc: West Tennessee

Posted 08 April 2012 - 07:41 PM

I have a 60mm aperture reduction mask for my Carton 100mm f/13, which would make it f/21.7. I've only had the Carton for a litle over a week, and moving over last weekend haven't had an opportunity to try it out at f21.7 yet. I imagine it should perform wonderfully as the center 60mm of the already outstanding 100mm Carton objective should provide awesome views.

That 80mm f/20 above is insane ;)

#8 Doug76

Doug76

    Long Achro Junkie

  • *****
  • Posts: 10839
  • Joined: 05 Dec 2007
  • Loc: Refractor Heaven

Posted 09 April 2012 - 04:21 PM

My Carton 60mm f/20 is awesome, and as the OP says, apo-like views. This one gets buried with me! :lol:

#9 strdst

strdst

    Soyuz

  • *****
  • Posts: 3948
  • Joined: 23 Mar 2008
  • Loc: Oregon Territory

Posted 10 April 2012 - 10:30 PM

Hi Bill,

I forgot to get back to your thread...sorry... the collimation is perfect. As fine as I've seen, a remarkable 80mm scope.

other keith






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics