Zero Optical Path Binoviewers

[niallk]

Hi,

Anyone on here use these?

https://www.teleskop-express.de/shop/product_info.php/info/p10297_TS-Optics-Binoviewer-1-0-magnification-zero-optical-path-and-erect-image.html

I'm considering for my Lunt LS50.

Concerned about internal reflections / scatter for Ha use.

A secondary use would be planets in my 15" dob (if they ever come back... )

[Geoff Barnes]

A shame you've had no response yet Niall, I was hoping for  a few opinions myself. Surely someone has used them on here?

 

[Floater]

I, too, have been looking for any response.

A similar question was asked a couple of weeks back and there was no reply. ?

[niallk]

I nearly pulled the trigger before. Saw a review recently in one of the astro mags: I think reflections could be a potential concern...

If solar activity shows signs of picking up, I might go for it.  I know that could be a while off still ?

[Floater]

I believe there are some references to these BVs on Cloudy Nights - and not all complimentary.

[niallk]

Yeah... There are many opinions from people who have not used them there too!!

I read more than one report of imbalance in brightness - in what I understood to be a nominally symmetric design??

Then I more recently read a S@N review (I think) which was actually quite positive - at least for DSOs in a 16" dob.

I've flip flopped on these, and I guess I wanted to fish for opinions I trust

I'm guilty of really wanting them to be good, but knowing in my heart that there's a price with complicated optics... at least at this price which are not designed by TeleVue!

Hmmm... I'll hold off for now i think ?

My first look through a Ha scope was a 60mm Lunt with a 50mm front mounted etalon, through a TeleVue binoviewer with tv plossls. It was absolutely exquisite!  I'd love a poor man's approximation in my LS50DS.  I get great views mono, but know what my maxbright did in my 10" on planets.  Just can't reach focus with it in my Lunt, unfortunately...

 

[Floater]

I’m not sure what you mean, Niall, about not reaching focus.

I can reach focus with my WO binoviewers in the Lunt 60 using a WO 2x ‘nosepiece’ or using a 2.5x Powermate. Longer eyepieces help to mitigate the resultant high magnification. Mostly I use TV plossls.

Certainly no chance of focussing without the Barlow in the optical train and anything less than 2x is not sufficient.

Wish I could compare my view with the one you had with a TV binoviewer ... ?

[niallk]

Cheers - it seems like the LS60 is what's required to reach focus with binoviewers - and is often cited in what I've read as one of the reasons, beyond raw aperture, to go for the 60mm: as I found out, it's widely reported that it's "not possible" with the LS50.  I run up against 'inwards focus' limitations ie making the path shorter.  Neither my 2.6x GPC or my 2.5x PM are successful.  Ive tried re ordering the blocking filter/GPC ahead of the BV.  Ive tried in both the stock + Moonlight upgrade focussers.  The only option I've seen stated to work for the LS50 is from Siebert optics.

I'll be very glad to hear that I'm wrong - I haven't read that any of the other Baader GPC options would help