BTX Binoviewer for ATX scopes (1 Viewer)

Ok, Henry, That's what I thought.

I've had exactly the same thing as you. If unused eye sees too much light or too distinct a pattern, it becomes a burden for my brain to filter that image out. If the eye sees an out-of-focus blob of black or grey, the image from the dominant, viewing eye completely dominates visual processing and viewing is easy and fatigue-free.

For me, this has been a very important improvement of viewing comfort and viewing endurance. Like the aiming device, the self-made "ambidextrous blinder" has become an essential part of my birding gear.

Kimmo

Heard from Brighton public camera obscura operator.
This is a high quality Sinden optics (previously with Grubb Parsons, Newcastle?) 12 inch f/18? objective. 5.5ft table. 17 degree field of view unmagnified.
Some of these were exported I think.

Minimum focus 100 yards on table, (although closer possible off the end of the viewing table), and magpies and gulls are small at 100 yards, and using the table magnifier is not easy viewing birds.

Apparently binoculars and spotting scopes are better.

So it would take a very sophisticated high quality variable magnification Dall type camera obscura for bird watching.

The views in the dark attic of the outside, say watching a cricket match 500 yards away were wonderous.
A grain free 4ft? image in full enhanced colour and a moving picture with flowers and grass swaying were amazing. I suppose directional microphones could be added. I have never had a better viewing experience. Made in 1935 after the 1934 house was specially built with a very high loft to house it on top of the hill. 108mm f/30 objective corrected for 4 colours with specially selected glass.
But this is beyond normal people to construct such a very high quality device.

So sorry. It doesn't seem that a bird watching camera obscura is viable, at least not easily.

There are only a few operating camera obscura in the U.S. Many are historic and not operating now.

Personally, I don't use binoviewers.
Horace Dall did make one, and I think his design was copied by others.

I don't watch the birding optics rumors or announcements very closely these days, so I'm arriving a little late to the discussion here.

These are the key factors for me:


So that's ~$4748 for a 6 lb. instrument--close to 5 grand with tax, which I end up paying at the end of the year. Of course one can elect to use one of the smaller and lighter objective modules, but personally if I were to get this I would want the maximum aperture and resolution for binoviewing. I cannot easily afford very many toys in this price range... As nice as I'm sure the BTX unit is, I'm not dying to have one. There are other things that would be higher on my wish list, including world travel.

One interesting item for comparison is the upcoming APM 70mm APO binocular. These binoculars are a little heavier (~7.5 lbs++ depending on the eyepieces used), but still "in the same ballpark" as a potentially usable rig for birders. The Swarovski would have the advantage in weight; the optics are surely superior; and you can enjoy a single quick focus control with the spotting scope. And of course you get that amazing Swaro quality control and customer service, etc. But hey, the APM binoculars are way more affordable--less than half the cost of the Swaro rig, including a pair of eyepieces. Optically, I expect with the ED/triplet objective on the APM binos will make for a very nice view. Personally, I find a pair of binoculars like this a more flexible and appealing tool, especially if you use them partly for astronomy. Of course focusing the APM binoculars would be less convenient when used for birding, with the individually focusing eyepieces, but I would appreciate the ability to configure the APM binoculars for a 4° FOV--more than twice as wide as the Swaro rig.

I think the convenience of a single center focus is a pretty huge factor for birders. And 6 lbs. is a manageable load for a short stroll, especially remembering the modular advantage of the Swaro kit: You could carry the BTX in a fanny pack while you walk with a standard spotting scope with mono-eyepiece. So I have to admit, for strictly birding, the BTX would be much nicer, if you can swallow that price--gulp.

Dave

What is the logic for big binoculars?
The stereo aspect has to be minute for longer distances, while the collimation requirements are stiffer.
Would not a telescope/binoviewer combination be more robust, cheaper and easier to make as well as lighter, while offering better performance and being more user friendly?

henry link said:

Thought I remembered seeing an earlier effort at a binoviewer/spotting scope. A little Googling turned up this from 2008.

http://bulletin.accurateshooter.com/2008/07/new-binocular-spotting-scope/

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From a post on CN I remembered this as also that I changed some e-mails with the Olivon Europe few years ago since found that they were developing a binoviewer for spotting scopes. Things got lost but today I found it at http://www.olivonusa.com/product/olivon-bino-viewer-w32mm-plossl/ - AFOVs should be limited but includes 2 barlows/OCS/Glass path correctors... Someone want to test it and let us know...3

I got to try the BTX briefly today. I must say this is a pretty remarkable piece of engineering!

The Amici prism and all the other glass in the light path somehow managed to do their job without coming in the way of a clean image, and it is definitely easier to read detail out of the image with two eyes. This was clear both outdoors and indoors, with both birds and USAF 1951 slides. Also flying birds as well as ones on the ground or sitting on a branch.

The BTX 95 is, of course, rather on the heavy side, but quite manageable on a tripod-harness, and also compact enough that I could easily carry it around for quite some distances as well as have it on my back while biking. Setting up the IPD is easy, as is diopter correction, and I had no difficulties merging the image. The attached aiming device works like a charm. You view your target over the scope eyepieces with the aiming device in front of your right eye, with your left eye seeing the target area, and when the fancy star-like pattern you see through the device is superimposed over your preferred target, the target is centered in the view. Much easier done than explained. My hat off for Swarovski for a truly functional improvement, which I hope they will make available for the ATX/STX zoom eyepieces also.

The forehead brace, on the other hand, I found largely useless and mostly viewed with it adjusted low enough that it would not touch my brow. The reason for this is that while it adjusts just fine and feels sort of comfortable to lean against, it efficiently transmits the small but unavoidable tremors of my head into the scope, thereby making the image vibrate. With a good tripod and video head, the image is simply more stable if I don't let my face touch the scope.

Comparing the image directly to an ATX 95 with the 30-72x zoom, the ATX image looks brighter, crisper and more contrasty, but you see more in the target with the BTX. For me subjectively, the image also looks significantly bigger through the BTX. To get a similar impression to the 35x BTX, I had to zoom the ATX up to well over 40x, more like 45+. Also indoors, when viewing the resolution target, with the BTX 95 at 35x, we could resolve the pattern (G3/E6) that tends to be the limit of good specimen of Diascope 85's an Kowa 883's at 60x. With the BTX and the 1.7x extender, we got very close to ATX95 @72x territory.

There does seem to be somewhat more CA in the BTX image compared to the ATX, and this was also visible on the glitter point star tests. The good news was absence of other prism artifacts such as prism lines, and best-focus glitter points were clean and free from any kind of spiking.

Likewise, when trying the 1.7x extender on my ATX 95, it looked like CA increased over the basic scope, but I did not do rigorous comparisons on equal magnifications yet. Indoors, in quick resolution target trials, I could get at least two more elements on the USAF slide with the 120x of the extender, which is about what I had expected. Outdoors the conditions today, with some considerable heat haze, were not suitable for the extender to show its power, but I have no doubt that in more stable atmospheric conditions it will give the scope some worthwhile extra reach.

Kimmo

Thanks Kimmo!
Now, if Swarovski would produce a variable extender with at least 1-2x zoom (remember that the Nikon FSA-L2 is 3.5x zoom, although also an image erector...), I would be tempted to get a BTX, even being angled...3
With such an extender, Swaro would be ahead of the concurrence like with the BTX.
For my type of birding I need zoom and power. Some years ago I tested a Docter bino zoom version and preferred my scope for cr-birding since allowed higher mags - don't remember if I still used a Nikon ED78 with the 25-56x zoom or already the Optolyth 100...

opticoholic said:

But hey, the APM binoculars are way more affordable--less than half the cost of the Swaro rig, including a pair of eyepieces. Optically, I expect with the ED/triplet objective on the APM binos will make for a very nice view. Personally, I find a pair of binoculars like this a more flexible and appealing tool, especially if you use them partly for astronomy. Of course focusing the APM binoculars would be less convenient when used for birding, with the individually focusing eyepieces, but I would appreciate the ability to configure the APM binoculars for a 4° FOV--more than twice as wide as the Swaro rig.


Dave

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The APM binos are a doublet apochromat using FPL-53 glass. I believe the Swaro's spotters (both *TX and the *TS) are also a doublet. They are noted as weather resistant but not sealed/purged.

Depending on the eyepieces used, as you've noted, you should get some high quality terrestrial views from these.

It would be interesting to see if you can use some of the fixed FL spotting scope eyepieces on these binos (with 1.25" adapters). That being said, price aside, i'm doubtful if these would have the same level of functionality as the ATX/BTX combo in terms of portability and field use.

I'm also curious on how the ATX 95mm/BTX combo performs for astro use. I recently purchased the Kowa flourite Highlanders for use when we're camping etc. They perform double duty as terrestrial binos for long distance viewing as well as astro gazing on those clear nights. I still have carry them in a reasonable pelican case. The Swaro's would be far more portable and compact to store.

cheers
Jeelan

It strikes me that where the Binoviewer will really come into its own is seawatching. I'll be interested to see how many hardened seawatchers adopt these as the kit of choice and whether the 85mm body with the wider 30x view will be favoured over the larger 95mm objective and the 35x mag.

Hi from Italy!
I've at binomania headquarters a specimen of Kowa Highlander, one of Docter Aspectem and the new Swarovski BTX!!!!
I hope to send you some images this evening.
During the week-end i will have an event with some passionates. I will publish a small video on binomania facebook page and a short preview with our impressions.
Thanks in advance for the attention!
Pier

Pier,

Looking forward to reading your comments and seeing the pics.


...and I like the part about "your passionates". Gotta love translation software.

Just be careful around those passionates! Things could get steamy (and I don't mean misted-up eyepieces)!

Grando said:

Just be careful around those passionates! Things could get steamy (and I don't mean misted-up eyepieces)!

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oo

Hello from Italy, guys. Here is, in brief, my first impressions. At dusk the Swarovski (ATX 95+ BTX) is less bright, I say of a 25-30% in less respect the Kowa Highlander Prominar and the Docter Aspectem ED. This was obvious. It appears to provide the brightness of a good 70 mm binoculars.
I seem to have more 'chromatic aberration respect the other two binoculars, but I have to make most' accurate verification. As an example the lunar limb has more 'colorful glow in the Austrian product
Of against the Swarovski is light, very light, less than 3000 grams, it is disassembled into two parts and allows you to quickly focused.
I think that the single focus system is the feature that I liked the most. It is used as a normal spotting scopes. Docter Aspectem and Kowa Highlander, however, have the focus for both eyepieces.
I think it's the ideal choice for those who already own an ATX form (at least 85) who should aim for a high-magnification binoculars, I am again very much undecided because i love my Aspectem and Highlander. Today I go out to look again. Excuse me for my poor english..
I hope to publish a review on Binomania next week.

binomania said:

... At dusk the Swarovski (ATX 95+ BTX) is less bright, I say of a 25-30% in less respect the Kowa Highlander Prominar and the Docter Aspectem ED. This was obvious. ...

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Hi Pier,
That is what to be expected but for most on this forum the interest is knowing about the perceived light compared to the normal ATX... We know that the light is split for the 2 eyes but we also know that the brain "recover" part of that light.

I did much cr-birding until the dusk (I continued always after my colleagues had stopped long ago...), and the difference on reading codes of a 80 to 100mm was about 5 minutes, so not a big deal as much it could be expected for normal birding. Now image quality and magnifications make a huge difference!

As I told before, the BTX is much more practical for active birding than both binoscopes.

Hi to all.I've published my impression on www.binomania.it.

Inviato dal mio SM-G935F utilizzando Tapatalk

To BTX or not to BTX?

I took a couple of weeks to update my http://www.pt-ducks.com/cr-telescopes.htm#CR-binoviewing info with a BTX small test and comparing it to my STX as also to my CR-binoview combo. I found some interesting points that no one mentioned until now:
- there is absolutely no ghost images at all!!!;
- within some lowlight conditions the BTX bested my STX!
More info and photos at the page.

In Focus (and some other UK dealers) now have limited stock of the BTX eyepiece module available to buy. Please visit the Retailers and Dealers Offers forum for more information.

Regards, Bruce and the In Focus Team

Many thanks Bruce. Do you have the 1.7 extender yet?

Unfortunately not yet.