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

Celestron omni 2x barlow have filter threads?

  • Please log in to reply
6 replies to this topic

#1 avhjr

avhjr

    Sputnik

  • -----
  • topic starter
  • Posts: 30
  • Joined: 22 Feb 2016

Posted 22 October 2020 - 03:52 PM

The celestron omni 2x barlow seems to have a bottom part that can be unscrewed and added directly to eyepieces for 1.5x.  However when it is not unscrewed are there threads to add a filter?



#2 Ernest_SPB

Ernest_SPB

    Apollo

  • *****
  • Posts: 1,472
  • Joined: 13 Nov 2010
  • Loc: St.-Petersburg, Russia

Posted 23 October 2020 - 03:27 AM

yes,.. between lens block and Barlow body.


  • Jon Isaacs and CeleNoptic like this

#3 CeleNoptic

CeleNoptic

    Surveyor 1

  • *****
  • Posts: 1,516
  • Joined: 20 Dec 2007
  • Loc: Mid-Atlantic, Bortle 7

Posted 23 October 2020 - 04:12 AM

Agena says No Filter Threads at Bottom of Barlow Cell, but as Ernest pointed out above there're filter threads between the Barlow cell and the tube. So if your filter(s) threaded on both sides you can sandwich it(them) between the eyepiece and the Barlow cell. Although it'll increase power beyond 1.5x. At the same time the 1.5x is just a guess, depends greatly on eyepiece. FWIW, from my experience with a similar shorty 2x GSO Barlow, its cell being screwed into eyepieces I had tested worked closer to 1.6x.



#4 jc482p

jc482p

    Explorer 1

  • -----
  • Posts: 60
  • Joined: 28 Jul 2020
  • Loc: northern NJ, USA

Posted 23 October 2020 - 09:14 PM

I have a Celestron Omni 2X Barlow.  When I got it, the way it came was a top part and a bottom part, both silver, and both screwed on to opposite ends of the black lens cell.  It's weird to me that in the Agena photo, my top and bottom parts are screwed directly together, and then the black lens cell is screwed to the bottom of my bottom part.

 

The way that I got my Barlow, when it is not unscrewed, I can try to screw a filter onto the bottom of it, because the bottom (silver) part is threaded.  The bottom threaded part is the enclosing circle and the filter threads have to be the enclosed circle.

 

If I screw together my Barlow the way it looks like Agena has it, so the bottom part is the black lens cell, then I can also try to screw a filter onto the bottom of the black lens cell  The bottom threaded part is the enclosed circle and the filter threads have to be the enclosing circle.


Edited by jc482p, 23 October 2020 - 09:29 PM.


#5 BFaucett

BFaucett

    Surveyor 1

  • *****
  • Posts: 1,954
  • Joined: 12 Jul 2014
  • Loc: Houston, Texas

Posted 24 October 2020 - 01:19 AM

As an example, the Orion Shorty 1.25" 2x Barlow has filter threads on the end of the Barlow lens segment:

 

download-enlarged-3.jpg

closeup-3.jpg

Quote from Orion's website:

"You can even use 1.25" eyepiece filters with the Orion Shorty Barlow, thanks to its filter-threaded barrel."

Product page at Orion: https://www.telescop...2160/p/8711.uts

Photo from Orion's website. I added the text and arrow to the image. 

 

 

Compare that to the Celestron Omni 1.25" 2X Barlow:

 

celestron omni 2x.jpg

Product page at Astronomics: https://www.astronom...-eyepieces.html

Product page at Amazon: https://www.amazon.c...s/dp/B00008Y0TM

Photo from: https://www.jumia.sn...ns-2593239.html  (scroll down towards the bottom of the LONG page)

 

 

I don't have the Celestron Omni Barlow but I do have the GSO 1.25" 2x Shorty Barlow from Agena. It looks the same as the Celestron. The GSO does NOT have filter threads. 

 

GSO 1.25" 2x "Shorty" Barlow:

 

GSO 2x Barlow.jpg

GSO 1.25" 2x "Shorty" Barlow

Product page at Agena: https://agenaastro.c...arlow-lens.html

Photo from Agena's website.

 

 

I have the Orion Shorty Barlow. The Barlow lens element can be removed and screwed onto an eyepiece to use it as a 1.5x Barlow. I frequently use it that way. My GSO Shorty Barlow can also be used that way but it just doesn't have the filter threads.

 

 

barlow lens on eyepiece.jpg

"A really nice feature of this GSO barlow is that the barlow element is housed in a separate metal cell at the bottom that can be unscrewed from the upper tube (see photos). You can then screw the barlow cell directly into 1.25" eyepieces with a standard 1.25" filter thread to increase the magnification of that particular eyepiece while still maintaining a low profile. When screwed into an eyepiece, the barlow will yield approximately 1.5x of magnification."

Photo and text from Agena's website: https://agenaastro.c...arlow-lens.html

 

 

A photo of one my eyepieces:

 

 

20201024_021031-cropped-resized-3.jpg

Meade 5000 UWA 5.5 mm, Orion Shorty Barlow lens element, #21 Orange filter

 

 

Bob F. smile.gif

 

 


Edited by BFaucett, 24 October 2020 - 02:51 AM.

  • Jon Isaacs and Second Time Around like this

#6 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 88,178
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 24 October 2020 - 02:42 AM

Just something else to think about:

 

Adding a filter to a barlow makes is somewhat longer and increases the chances that it will hit the mirror or prism of a diagonal.  

 

Probably not an issue with a shorty barlow but I would check before using it.

 

Jon


  • chemisted and BFaucett like this

#7 BFaucett

BFaucett

    Surveyor 1

  • *****
  • Posts: 1,954
  • Joined: 12 Jul 2014
  • Loc: Houston, Texas

Posted 24 October 2020 - 03:33 AM

Just something else to think about:

 

Adding a filter to a barlow makes is somewhat longer and increases the chances that it will hit the mirror or prism of a diagonal.  

 

Probably not an issue with a shorty barlow but I would check before using it.

 

Jon

 

Good point. Thanks, Jon.

 

Bob F. smile.gif


  • Jon Isaacs 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