Binoviewer report

[gaseous (Patrick)]

Last Friday saw the delivery of my new binoviewers from Telescopes & Astronomy in SA, and as is usual, the clouds/rain decided to roll in. Needless to say there was a week of high dudgeon as I waited for this insolent weather to cease and desist, so I didn't get to bust them out for their maiden voyage until last night. They're a pretty standard OEM binoviewer which come with some fairly rudimentary looking 30mm eyepieces, and two 1.25" barlows: 1.85x and 3x.
They appear well made, and adjust smoothly, with a twistable eyepiece locking mechanism and adjustable focuser for each each. The moon last night was 100% full, so I was mainly interested to check out Jupiter, the Moon, and maybe a few other objects to get a feel for them.
Firstly, the small barlows are essential to reach focus in an 8" dob. No chance otherwise. I honed in on Jupiter with the 30mm ep's and the 1.85x barlow, and was pleasantly surprised - the view was very sharp and showed nice banding on the planet even at a fairly low power 74x mag. I then popped in the 3x barlow for 120x mag and the views were still very good. For a comparison, I swapped over to an ES 11mm 82° eyepiece for a monocular view at about 109x, and the binoviewers didn't appear to lose much, if anything, over the single "quality" eyepiece. Seeing wasn't great, but there were sufficient moments of calm to appreciate that there wasn't an appreciable difference between them. I then popped the BV with the 3x barlow into the back of my 2" 2x barlow for 240x mag, and while the upper air turbulence was obviously more pronounced, the views were still great and better than I'd expected with what appear to be some very low-tech eyepieces. There is a lot of talk about BV's reducing the amount of light coming through, and while this is true it didn't appear particularly noticeable on Jupiter, and probably even helped bring out some of the detail given it's natural brightness.
I then focused on the Jewel Box cluster NGC4755. I wasn't anticipating spectacular viewing (given the previous comment about light reduction), but overall the views weren't too bad. The stars probably weren't as crisp as you'd expect from single-eyepiece observing, but that may come down to inexperience on my part - the BV's have individually adjustable focussing for each eye, so coupling that with getting the correct IPD is a bit of an art I'll need to master. The bv adjusts very smoothly, so altering the IPD can sometimes alter the focus of each eye, and vice versa. Again, there wasn't a lot of difference in the light coming through compared to a single EP, although the background was considerably darker.
Not expecting much joy, given the natural light pollution coupled with a full moon (my admittedly dodgy SQM app gave a reading of 18.08) and the fact that nebulae aren't really the standard target for BV's, I swung over to Eta Carina with a DGM NPB filter. I must say I was quite surprised at the level of detail achievable, and when I popped in a single eyepiece for a comparison, again the alleged light loss through the BV wasn't as extreme as I anticipated. I tried a pair of standard 25mm plossls (the type you get with a new scope), and they were quite loose in the BV due to the recess in the barrel - I'm hoping it's for this reason that there was absolutely breathtaking coma across 90% of the FOV. Back with the budget 30mm ep's and all was well again. I could reasonably expect that under a dark sky, the BV's on brighter nebulae may be quite enjoyable despite the relatively high magnification.
Last target was the moon. I wouldn't say the effect was "3D", but it was certainly interesting and more immersive than single ep observing. With the moon being so bright and taking up so much of the view, it highlighted the need for getting the correct interpupillary distance as close as possible otherwise there are minor "blackouts" (I'm sure there's a technical term for this). I think the moon at quarter phase will be quite stunning.
Overall, I was very pleased with these low-range bv's, given the conditions and the eyepieces I was working with. The reported light loss was considerably less than I was expecting, and although noticeable, it was certainly not overly detrimental to viewing even targets not normally associated with BV's. I'll need to spend some time getting them properly adjusted for my eyes, as this was a fiddly process, but overall I think I'll be getting a lot of enjoyment from them. As a final note, I would say that the ease/comfort of using two eyes cannot be overstated, particularly if you're observing for extended periods of time.

[SkyWatch (Dean)]

Thanks Patrick,
A nice report! As you say, they do take some getting used to, and are difficult to share with other observers due to having to change IPD and focus.
Hopefully they will really make a difference in dark skies!
It will be interesting to see how they go with better quality eyepieces. (I see a pair of 21mm Denkmeier's are for sale in the classics at present! )
What telescope were you using?
All the best,

Dean

[Atmos (Colin)]

Most of my observing at the moment is down with binoviewers looking at Luna and planetary with some double stars thrown in.

The light loss really isn't noticeable for the most part, although it is halved for each eye our brain does a very good job at recovering most of that back anyway. In some ways it helps as we're naturally used to looking with both eyes!

As you have said, comfort is such a big thing with observing. Closing one eye for an extended period is uncomfortable while keeping both open (and monoviewing) is terribly distracting in suburbia.

[gaseous (Patrick)]

Thanks Dean/Colin,
Currently using them I am 8" collapsible Skywatcher dob Dean, although I've also got a 16" of the same model which I haven't tried the bv's in yet. You're right Colin, I was surprised at the comfort difference between single and double eye viewing - you don't expect such a difference until you do it and it makes it much more natural. Gotta get some decent low FL eyepieces - i'm thinking 30mm +. I was thinking of getting a second Baader zoom, but the mag might be getting a bit high, particularly in the 16".

[Atmos (Colin)]

Just remember that you cannot got over 1.25" eye pieces. Although expensive, about the Largest field stop you can use is TeleVue 24mm Panoptics. 24mm and 68°, haven't tried them but I've heard it's just swimming in wide field bliss

[SkyWatch (Dean)]

The Televue 32mm Plossl also has the maximum field stop for a 1 1/4"/32mm eyepiece (i.e.: 27mm), and gives the same field as the 24mm Panoptic, (but obviously at lower power), and at less than 1/2 the price...

[gaseous (Patrick)]

Thanks Dean - just had a look on Bintel - gee they don't miss with the Panoptics do they? 32mm plossls looking much more feasible.

[LewisM]

Are these the "multi-branded" ones - either they come branded Celestron, Sky Rover or unbranded usually. eBay seller in Sydney had these for $200, and almost considered a pair (having used a televue binoviewer, I may be more inclined to save up for now).

Do these appear to have mirrors or prisms?

I certainly got a VERY 3D feel on the moon and planets using the TV binoviewers, so, if you say you did NOT get that feeling with these, I may indeed hold off. I just don't feel inclined as to the price

[dannat (Daniel)]

lewis they use prisms

[SkyWatch (Dean)]

Originally Posted by gaseous

Thanks Dean - just had a look on Bintel - gee they don't miss with the Panoptics do they? 32mm plossls looking much more feasible.

Yeah, the 32mm plossls are very nice: but not cheap either! Televue just finished their annual (?) sale, where they were all 15% off- so you might want to look for that next year. Claude at AEC has the TV 32mm plossl listed at $175 (see: http://www.astronomy-electronics-cen...ices_other.htm ), but I don't know if he would have two.
The 24mm Panoptics are lovely eyepieces (much better than the 19mm Panoptics in my experience), but you have to pay premium price for premium quality! The ES 68 degree series are cheaper and with similar specs to the Panoptics, but they might be too wide-bodied for a binoviewer.

All the best,

Dean

[gaseous (Patrick)]

Originally Posted by LewisM

Are these the "multi-branded" ones - either they come branded Celestron, Sky Rover or unbranded usually. eBay seller in Sydney had these for $200, and almost considered a pair (having used a televue binoviewer, I may be more inclined to save up for now).

Do these appear to have mirrors or prisms?

I certainly got a VERY 3D feel on the moon and planets using the TV binoviewers, so, if you say you did NOT get that feeling with these, I may indeed hold off. I just don't feel inclined as to the price

Hi Lewis, I wouldn't say it wasn't 3D, maybe just that I was spending a lot of time familiarizing myself with the adjustments possibly at the sake of viewing enjoyment - I daresay once the stuffing about is minimised, the views will be more captivating. As it was, Jupiter was an "oh wow" moment as soon as I got it focussed correctly. If a televue bv (at 3-4 times the price) has a commensurate improvement in views, then I can readily appreciate how good they must be.

[gaseous (Patrick)]

Originally Posted by SkyWatch

Yeah, the 32mm plossls are very nice: but not cheap either! Televue just finished their annual (?) sale, where they were all 15% off- so you might want to look for that next year. Claude at AEC has the TV 32mm plossl listed at $175 (see: http://www.astronomy-electronics-cen...ices_other.htm ), but I don't know if he would have two.
The 24mm Panoptics are lovely eyepieces (much better than the 19mm Panoptics in my experience), but you have to pay premium price for premium quality! The ES 68 degree series are cheaper and with similar specs to the Panoptics, but they might be too wide-bodied for a binoviewer.

All the best,

Dean

Cheers Dean, looks like another month of hiding the credit card statement from the wife is approaching!