View Full Version here: : Binoviewer with a Hangover

larry brockman
23-02-2007, 05:53 PM
I recently purchased a Binoviewer for my F8 Refractor. I was warned that I wouldn’t achieve focus without a Barlo or a Corrector Piece. I have a 2xBarlo , however, it provides too much over hang. So am searching for a 1.5 X Barlo or Corrector in hopes they will be smaller and more compact to cut back my over hang. Any leads would be appreciated,
Best Regards Larry Brockman :)

23-02-2007, 07:03 PM
The Orion shorty plus 2X is fairly short, about 75mm total length with about 43mm barrel sticking out of the diagonal. Alternatively you could look at Siebert optics OCA's; they have one which attaches to the nose of your diagonal adding no extra length to you diagonal. http://www.siebertoptics.com/SiebertOptics-OCA.html

23-02-2007, 11:28 PM
I would try a 1.25" diagonal and screwing the corrector lens onto the focuser end of the diagonal instead of the BV nosepiece.

larry brockman
24-02-2007, 02:11 PM


24-02-2007, 02:55 PM
Yep, I recently got a Denk "big easy" binoviewer and using it with a refractor the instructions say to place the "optical corrector" onto the front end of the diagonal...worked like a champ for me in the Skywatcher ED80!

Good luck...

02-03-2007, 03:51 PM
There seems to be some doubt whether BVs work with Newtonians with a low focal ratio.
The William Optics website says "most" Newtonians are OK. Talks here are that possibly an extension tube or Barlow add-on is needed. But no one really seems to know.
Or any other brand?
Rather than buy and be disenchanted, does anyone have the experience to share?


02-03-2007, 04:27 PM
Leo and Larry,
From my own personal experience I can safely say the WO comment about working in most newts is very optimistic! Out of 4 I've tried, zero worked, with their supplied 1.6X OCS. I believe it does work with a short extension tube between the OCS and the BV, but the magX will increase further. I got it to work with a 2X barlow and no OCS, but this gives more like 4X. Most of these generic BV's will be the same.

In the end, I contacted Harry Seibert and ordered a Multimag OCS. This gives me 1.25X, 2X, 3.5X with newts and 1.25X, 2X, 3X and 3.5X with the refractor. Works in ALL my scopes now, including a 6" F8 refractor. The Seibert OCS is FAR superior to the WO one optically, btw. This WO/Seibert combo works very well for not that much money. The supplied WO 20mm eyepieces are reasonably good.

Clear skies.

Forgot to mention, the Seibert OCS also improves focus/sharpness at the edges of the field with all mag settings, and as far as I can tell with all eyepieces I've tried so far.

02-03-2007, 08:18 PM
That Siebert website is worth a visit.
A "can do" attitude pervades. So given some feedback elsewhere, I would buy there if they have a solution....possibly the same one as you chose.

13-03-2007, 11:20 AM
I tried the WO binoviewer last night. Mixed results.

1. To focus the Meade F4 SN10, it required not only the supplied WO X 1.6 corrector but also a long 2X Barlow, both together. And then it was nearly at the very end of focuser travel with a 20mm eyepiece, effectively a 3.2 X, SN10 focal length 1012mm.
This gave a narrow filed of view which delets the advantage of an F4 10" Newtonian for nebula etc.
But it will focus...
An extender might help
(By the way, a smaller Newtonian (150mm X 1400mm) will focus with the WO 1.6X corrector, but not at all without it. That one has a Barlow in the focusser.)

2. Any comments or comparisons with the Burgess MK24 ?
Burgess has a wider clear aperture, the OCS supplied is 2.3X..not as bad a X 3.2, .....But will it focus on the F4 SN10"?
Would the supplied extension tube help?

3. The Siebert MultiMag OCS option I have in mind would be in addition to one of the above BVs.
Sieberts suggested "Ad#2 either the standard or multi-mag OCA. (SBW-1.25x for $99 or SBW-1.25x-3.5x for $134) This should work with both 2" and 1.25" setups with a slight change in configurations. "
4. However I do not know whether all those varieties of magnification would work with a Newtonian F4, using either WO or Burgess BV.

5. Given that the MK24 Burgess pack costs an extra $160, does anyone know if the performance is better?

Let's see who has some ideas.


13-03-2007, 06:22 PM
Hi Leo,

please see my PM.

The problem I see is trying to also get low power use with these BV'ers. I really see Seibert Optics as being your only solution, whether you are happy with 1.25X as the lowest magnification factor or lower at around 1X. Otherwise, you would have to look at getting a different BV (Denk perhaps, to get around 1.2 or 1.3X).

Clear skies

16-03-2007, 05:45 PM
Last night the SN10 focussed near the end of travel, with the William Optics X1.6 corrector inserted right down in the focuser. The SN10 2" tube adjacent to the focuser had been removed. All OK.
I will still get the Siebert Multi-OCA to give some variety in magnification. Thanks to all.