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

William Optics binoviewer cannot focus with 16" Lightbridge

  • Please log in to reply
6 replies to this topic

#1 Speo

Speo

    Vostok 1

  • -----
  • topic starter
  • Posts: 139
  • Joined: 29 May 2019
  • Loc: Toronto, Canada

Posted 21 June 2021 - 01:39 PM

I have a William Optics binoviewer and I tried to use it for the first time with my new (for me) 16" Meade Lightbridge, but I could not reach focus. I am missing 1/16 of an inch inner focus, or maybe less.

I ran a test by removing the 2" to 1.25" adapter, and held the binoviewer by hand in the center of the focuser and I was able to reach and pass focus point by a very small fraction, just enough to see that the image starts to loose clarity.

 

After seeing that all I need is a very small extra inner focus, I tried to play around with the WO stock 1.6x barlow nosepiece and to my suprise, I can reach focus with the 2" to 1.25" adapter if I turn loose the barlow 3 complete turns. This moves the barlow slighly forward and away from the binoviewer. Does this barlow movement forward affect anything else, like image quality, or cropping the light cone?    Is it OK to use it like this, or should i look for a better option?


Edited by Speo, 21 June 2021 - 01:51 PM.


#2 jmillsbss

jmillsbss

    Viking 1

  • *****
  • Posts: 723
  • Joined: 03 Dec 2018
  • Loc: New Albany, Mississippi, USA

Posted 21 June 2021 - 01:55 PM

You could measure the distance of the gap you have produced by backing out the barlow attachment then see if you can move your primary back that far.  You've probably got enough range in the primary mounting cell, but you don't know if it's enough until you try it.  Essentially you'll be moving the primary further down in the mirror cell. Easy way to do it is simply count the number of turns and do the same on all three points, re-collimate then see where you are.  It won't cost anything, just a little time.

 

Alternately, I sold my WO binoviewer and bought the Orion Linear BV'ers.  They're really the simplest thing in the world.  No GPC or barlow required.  I bought a pair of 65 degree APM EPs and a 0.66x GSO reducer and a 2x Powermate and I have three powers that work flawlessly in all 3 types of my scopes.  That may not be your answer, so I'd start with moving the primary and go from there.

 

Good luck!   J


Edited by jmillsbss, 21 June 2021 - 02:00 PM.


#3 jack45

jack45

    Gemini

  • *****
  • Posts: 3,352
  • Joined: 07 Jul 2003
  • Loc: Lacey WA

Posted 21 June 2021 - 02:11 PM

Siebert Optics has the, 1.25x/2x/3.5x OCA, it should work with your scope.

 

Clear Skies!



#4 eyespy

eyespy

    Mariner 2

  • -----
  • Posts: 286
  • Joined: 12 Dec 2017
  • Loc: BC Canada

Posted 21 June 2021 - 02:46 PM

Hi Jmill,

 

I think that Speo is running out of ‘in’ focus and therefore should move his primary mirror up the tube/cell closer to the diagonal.

 

Doug.....


Edited by eyespy, 21 June 2021 - 02:49 PM.

  • noisejammer and Adam Long like this

#5 Speo

Speo

    Vostok 1

  • -----
  • topic starter
  • Posts: 139
  • Joined: 29 May 2019
  • Loc: Toronto, Canada

Posted 21 June 2021 - 03:02 PM

Hi Jmill,

 

I think that Speo is running out of ‘in’ focus and therefore should move his primary mirror up the tube/cell closer to the diagonal.

 

Doug.....

Hi guys, yes, I am running out of 'in' focus and I got the idea. I have to adjust the primary to move it up a bit using the collimation screws.



#6 Tom Stock

Tom Stock

    Viking 1

  • *****
  • Posts: 909
  • Joined: 27 Jun 2010
  • Loc: Saint Augustine, FL

Posted 28 June 2021 - 04:45 PM

I put my 2" to 1.25" adapter on a lathe and removed 1/16".  This allows me to reach focus in my 16" lightbridge with the 1.6X barlow.  Using collimation screws is not a bad idea... I guess that might work.


Edited by Tom Stock, 28 June 2021 - 04:46 PM.


#7 Speo

Speo

    Vostok 1

  • -----
  • topic starter
  • Posts: 139
  • Joined: 29 May 2019
  • Loc: Toronto, Canada

Posted 28 June 2021 - 09:50 PM

I found a 2” to 1.25” adapter with a thin “shoulder” and I replaced the thumbscrew with a short set screw that I tightened with an allen key. I also raised the mirror cell a little bit by using the collimation screws.

Now I can reach focus with the bino and still have 5mm more in-focus travel, just in case I need it for other eyepieces.

 

Thanks for all the replies.

Attached Thumbnails

  • 57DC3A0C-AA13-41CF-8302-4B850B8C12BA.jpeg

Edited by Speo, 29 June 2021 - 11:28 AM.



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