Binoviewer opinion

[Michael131313]

Hello Everyone. I have a couple of questions about binoviewers. Would it be better to get a binoviewer like a William Optics to see how they work or save the money for better quality? How do you think they would work with my ES AR102 f/6 and my ES 10-inch hybrid truss dobsonian f/5?
Thanks very much for your help. Michael

[SkyHiker]

Hi Michael

It's tricky. I bought the WOs, it's good value but limiting at the same time. Two things to be aware of:

(1) The optical path is longer so you can only use it on scopes that have large backfocus, and
(2) The FOV will limit your choice of eyepieces to the low focal lengths.

IIRC I was able to use it on my 12" GSO astrograph with the 20 mm eyepieces without a problem. I was able to use them on my modified Z12 Dob only thanks to the fact that I had drilled an extra hole for the trusses that would give me as much backfocus as my GSO (for a camera). So, most likely you can't use it on your Dob unless you modify it somehow.

I would really have liked to use longer focal length eyepieces for bright and crisp views (less magnification) so I got two 32 mm eyepieces. As predicted by Lady Fractor, there was severe vignetting (the eyepieces had a larger field stop than the clear aperture of the binoviewer). A higher end binoviewer might not have that problem. She sent me a link one time to a better option for almost twice the price, but I lost it. In retrospect I would have got that one, though I'm happy with the cheaper WOs using the 20 mm eyepieces. Just a bit more magnification than I like.

Check out this thread for the details.

[SkyHiker]

The ones that I was thinking of may have been these. All I can remember is that they had red features on them. If you look at the description, they claim that they address the problems I mentioned. HTH.

[Michael131313]

Thanks very much Henk. The link has a lot of information that I will have to work through. So you don't think that the WO binos will work with my Dob? I appreciate all your help.
Michael

[Bigzmey]

I wanted to try BVs without breaking my wallet and went with the basic prism Orion BVs. Which are basically rebrand of WO BVs.

https://www.telescope.com/Orion/Orion-B ... binoviewer

After playing with them for awhile I realized that they suit me perfectly and I don't need anything fancier. They will work fine with your AR102, but you will need to use a barlow to bring them to focus.

The trick with barlow/glasspath corrector may work for DOB to. I don't have a DOB to try.

[Michael131313]

Thanks a lot Bigzmey. That will help me out in my decision.

[SkyHiker]

Thanks very much Henk. The link has a lot of information that I will have to work through. So you don't think that the WO binos will work with my Dob? I appreciate all your help.
Michael

Right, I don't think you can get focus unless you use a Barlow as Andrej noted. I just tried the 1.6x Barlow that comes with it on my Z12 (configured for visual), and I was able to get focus on a remote tree with lots of backfocus to spare. It will probably work for your Dob too.

The WO also comes with two 20 mm eyepieces, unlike Andrej's Orion and the expensive Orion that I linked. The eyepieces are bought separately. BTW I don't think Andrej's binoviewers are the same as the WO.

So, if you don't mind an extra 60% focal length for your Dob, the WO should be fine.

[Bigzmey]

Thanks very much Henk. The link has a lot of information that I will have to work through. So you don't think that the WO binos will work with my Dob? I appreciate all your help.
Michael

Right, I don't think you can get focus unless you use a Barlow as Andrej noted. I just tried the 1.6x Barlow that comes with it on my Z12 (configured for visual), and I was able to get focus on a remote tree with lots of backfocus to spare. It will probably work for your Dob too.

The WO also comes with two 20 mm eyepieces, unlike Andrej's Orion and the expensive Orion that I linked. The eyepieces are bought separately. BTW I don't think Andrej's binoviewers are the same as the WO.

So, if you don't mind an extra 60% focal length for your Dob, the WO should be fine.

There are many offerings of this style prism BVs on the market. They maybe not identical, by they are based on the same optical design and optically behave very similar.

In this case consideration is whether you want to have a pair of 20mm Erfles for extra $100 or to spend them on a pair of your favorite EPs and whether you want 2x or 1.6x barlow. Mine version of BVs came with 1.8x.

[Michael131313]

Thanks both of you for your help

[JayTee]

At Andrey's recommendation I too own a pair of the Orion BVs. My goal was to use them in my C11 for planetary and lunar observing and in that scope with two Agena SWA 15 mm EPs they work great. Couldn't ask for better.

[Michael131313]

Thanks JT

[Lady Fraktor]

As has been mentioned before a SC / Mak do not require a OCA due to the variable focal length of the telescope.
The linear BVs will work with just about any configuration but the clear aperture is very small.
The WO, Celestron, Stellarvue BVs work very well though you will have to check the clear aperture as it can be anywhere between 18-21mm somake sure to read the fine print!

These are a new option and comparable to the Baader Maxbright II with a 28mm clear aperture. I think the claimed lightpath is short though, I think it is about 10 cm longer but I will check later.
https://www.teleskop-express.de/shop/pr ... copes.html

[Lady Fraktor]

After a quick exchange with the designer, the lightpath of these new BVs is 128.2mm though the majority of sites list it as 118mm