Binoviewers and double stars

[Moonshane]

I began down the binoviewer (BV) route mainly as a means of achieving comfortable and detailed views of the sun and moon and they have certainly delivered in this respect. I then moved onto planets and have found the detail visible much enhanced using two eyes.

The briefest of peeks at DSOs has not really impressed me if honest but I have never really given it much time. Doubles were also tried and without much success really as there seemed to be a lot of off axis CA and blurring. However, after observing Jupiter the other night in good seeing I turned the scope (a 'champagne' 120ED) onto Epsilon Bootis (Izar) at 156x and the view was initially a bit blurred. I persevered a little and careful centering of the double created a well focused and superbly sharp image with textbook stars.

Realising that the seeing was very good, I put in the 8mm plossls and took the magnification to 292x and the view was the best I have ever had of this double. Stunning sharpness and a 'huge split'. Feeling confident I then turned the scope on Zeta Herculis and this normally challenging object was immediately and very obviously resolved. The view held well and only occasionally fuzzed out.

Moving on to another difficult double, Lambda Cygni, I found the split really quite obvious which was the biggest surprise of all. Doubles like Delta Cygni, Pi Aquilae and naturally Epsilon Lyrae were no match for this set up.

Maybe this is common knowledge to BV users but if you use them and have never tried doubles in good seeing then I'd definitely have a go.

[John]

Another tempation to try BV''s again (3rd time lucky ?)

[Moonshane]

LOL

One day you'll get a pair that 'click' I reckon.

 

[michaelmorris]

Thanks for the tip, I'll give this a go.

[Stargazer McCabe]

That's an interesting post. I too enjoy my BVs on Lunar and planetary. Never really persevered finding a solution for Solar and not tried much on doubles. 

But will do so as soon as I can...

[chiltonstar]

A general point re BVs but particularly applicable to doubles, do you need correction lenses on each EP to correct for any human eye differences (I don't wear glasses, but I can notice very slight astigmatism between one eye and the other). If you do, does this change the FL of the two EPs slightly and make it difficult to get coincident images for doubles?

Chris

[Moonshane]

I have a bit more (minor) astigmatism in one eye compared with the other and there's no difference that cannot be accommodated with the diopter adjustment. The only time I have had issues with merging other than at the start are when I have had too much red wine (it does seriously affect your ability to merge even when you have a 'normal' amount) and also sometimes when the BV eyepieces are not quite horizontal. The eyes (or rather the brain) are amazing at compensating for differences. My wife once walked about, speaking with various people with one of her mid blue sunglasses lenses missing and it was only when someone asked her what the flip she was doing and she took them off that she realised!

 

[chiltonstar]

Thanks for this Shane.

Is there a big difference in quality between the various BV setups sold?

Chris

[Moonshane]

I have only used Baader Maxbrights and really like them. The main differences are size of prisms and thus aperture of true field available. All the cheaper end including Maxbrights are approximately the same size and quality from what I read with the Baader mk4/5 and Denks etc being a step up in size of prisms but not necessarily quality. If you are not needing widest field then the cheaper end are all you need in my experience. I chose the Maxbrights due to the flexibility of the T2 connectivity.

 

[niallk]

I really enjoy my Maxbrights on solar system targets. Last weekend I had the privilege of looking through a TV BinoVue on a Ha setup with TV 20mm plossls: it delivered superb views. Zero conscious effort to merge images, the inter-ocular distance adjustment was so light, and solid mechanically.

[Moonshane]

I think were I to change ever, it would be these. My sole reservation is whether I could reduce the optical train length enough to get full disk views in my PST mod.

[Stu]

I must do more with my BVs on astro targets. I use them 99% of the time for solar currently, but agree that the few simple doubles I tried showed very sharply.

I've not looked back since getting my Baader Zeiss Mark IVs, for white light solar they are very sharp. I would assume the Prism quality must give similar benefits at high power as the Baader Herschel Wedge?

Unlike Shane and others, I cannot gain a benefit with them for planetary observing, the detail just isn't there, but for solar it definitely is, and as said my limited experience confirms the benefit on doubles.

[laudropb]

Very interesting report Shane. I really must press the button on a pair of binoviewers. Just can't make up my mind on which ones to get.

[Moonshane]

Personally my recommendation would always be for the Baader Maxbrights but a used pair - a wanted ad might generate some replies. I bought mine with a 1.7GPC for £120. The main benefit is the flexibility of the t2 connections. To my mind the main disadvantage of some systems is that they use a 2x barlow element which can equate to a 4x barlow element when combined with the BV distances. This reduces the possible fields in use.

I like to get full solar/lunar disk where possible and I can just achieve it with all my scopes (some with some margin) other than my 6" and 16" dobs both of which have 1600mm focal lengths.