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

Choosing between a Quark based refractor and a dedicated solar scope

  • Please log in to reply
32 replies to this topic

#26 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 15 March 2019 - 03:20 PM

 I wonder why Lunt went with EDs for their 80 and 100 scopes? David  

Do they also serve as night scopes?  If so that's perhaps the answer.



#27 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted 15 March 2019 - 03:21 PM

Just got in from some of the best h-alpha views I've ever had and that includes the demos at NEAF.  But I'm putting my impressions in the CFF hath arrived thread in REFRACTORS



#28 dscarpa

dscarpa

    Gemini

  • *****
  • Posts: 3436
  • Joined: 15 Mar 2008
  • Loc: San Diego Ca.

Posted 15 March 2019 - 09:39 PM

 I'd love to see a side by side with you're CFF 90-Quark and a  Coronado 90  3. David


Edited by dscarpa, 15 March 2019 - 09:41 PM.


#29 ValeryD

ValeryD

    Vendor (Aries)

  • ****-
  • Vendors
  • Posts: 1825
  • Joined: 26 Nov 2005
  • Loc: Kherson, Ukraine.

Posted 15 March 2019 - 09:52 PM

Just got in from some of the best h-alpha views I've ever had and that includes the demos at NEAF.  But I'm putting my impressions in the CFF hath arrived thread in REFRACTORS

I've read it.  Congrats with a small beauty.

 

BTW  let me tell you something more.

 

 First is that the F/30 ratio is not really a design speciafication for Quark or any another (regardless of manufacturer)  H-a etalon.  This F/30 is the maximum of the system "speed"  where H-a etalon (in your case - Quark) works OK.  If you will lower the F/D to about F/45-50 you will get significantly narrower bandwidth of your system (vs what you have at F/30) and so, a higher contrast and better details visibility.

 Secondly, you also will notice another important impovement - if at F/30 you see some FOV non-uniformity (due to imperfection of an H-a crystall) then at F/45-50 it become less noticeable! 

 

 To keep etalon at the highest contrast, you will need to set the tuning knob one or two clicks counterclockwise vs best position at F/30.  To keep the image brightness the same you will need

to use about 1,5x longer f.l. eyepieces.

 

 So, putting a 1.5x Barlow in front of Quark and reaching slower F/D at F/45-50 in return you will get two major improvements of your H-a system performance.

 

Hope this helps.

 

 

Valery


  • gnowellsct likes this

#30 BYoesle

BYoesle

    Fly Me to the Moon

  • *****
  • Posts: 6339
  • Joined: 12 Jun 2004
  • Loc: Washington USA

Posted 16 March 2019 - 10:35 AM

 

I wonder why Lunt went with EDs for their 80 and 100 scopes? David

 

I would assume (yes, I know) these lenses are more readily available or less costly from their OEM objective supplier.



#31 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted Yesterday, 02:26 PM

I've read it.  Congrats with a small beauty.

 

BTW  let me tell you something more.

 

 First is that the F/30 ratio is not really a design speciafication for Quark or any another (regardless of manufacturer)  H-a etalon.  This F/30 is the maximum of the system "speed"  where H-a etalon (in your case - Quark) works OK.  If you will lower the F/D to about F/45-50 you will get significantly narrower bandwidth of your system (vs what you have at F/30) and so, a higher contrast and better details visibility.

 Secondly, you also will notice another important impovement - if at F/30 you see some FOV non-uniformity (due to imperfection of an H-a crystall) then at F/45-50 it become less noticeable! 

 

 To keep etalon at the highest contrast, you will need to set the tuning knob one or two clicks counterclockwise vs best position at F/30.  To keep the image brightness the same you will need

to use about 1,5x longer f.l. eyepieces.

 

 So, putting a 1.5x Barlow in front of Quark and reaching slower F/D at F/45-50 in return you will get two major improvements of your H-a system performance.

 

Hope this helps.

 

 

Valery

Well at some point we I can give this a try.  I am unclear about the order of assembly.  Currently it is

 

telescope-ERF-diagonal-powermate-quark-eyepiece

 

Where should I put the barlow relative to the power mate?  If you think I should use a different order of assembly let me know.

 

I don't currently have a 1.5x Barlow.  1.5*4x powermate would get to f/41.  A 2x power mate * 4x powermate gets to f/55 which is not far off the f/50 you are talking about.  I can tell you that this is very high magnification because I did it once by accident and the were not terrific, but it was a cloudy day and there were trees.    The experiment would bear repeating 55*92 mm fl is only 5,000 or so focal length and about 127x with a 40mm eyepiece so I guess it's not excessive.  But I did notice that the solar disk was VERY BIG and it was a little difficult maneuvering.  But I suppose I should put the hand controller at a slower speed.

 

I'd also like to know what the F/D stands for.  I hate to confess such ignorance in public but there it is.  

 

Thanks for your advice,

 

Greg N



#32 gnowellsct

gnowellsct

    Voyager 1

  • *****
  • Posts: 14110
  • Joined: 24 Jun 2009

Posted Yesterday, 03:51 PM

I did find this Starizona 1.5x Barlow which looks like it would threat into a Quark etalon.  

 

So with this the optical train would be:

 

telescope-ERF-diagonal-powermate 4x-1.5x barlow-quark-eyepiece  

 

and would be about f/42  

 

I keep writing ERF.  What I actually have is the UVIR.  

 

thanks

Greg N



#33 George9

George9

    Apollo

  • *****
  • Posts: 1420
  • Joined: 11 Dec 2004

Posted Yesterday, 04:03 PM

I'd also like to know what the F/D stands for. 

I think he just means F=Focal length, D=lens Diameter, F/D = focal ratio = f-number.

 

George


  • gnowellsct likes this


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