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Prisms! S-P, Uppendahl, Abbe-Koenig..

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Old Tuesday 18th February 2020, 15:38   #51
Steve C
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Thanks for this Steve,

I actually meant 'not much room for a focusing lens in what we would regard as the usual position, if you used this arrangement in a binocular', clearly if this is what I meant, this is what I should have posted

Lee
I thought you had that figured out. I should have indicated it was a general info post on my part.
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Old Tuesday 18th February 2020, 15:53   #52
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I thought you had that figured out. I should have indicated it was a general info post on my part.
OK, thanks Steve, my brain has winter-blues. I need spring and need it soon!

Lee
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Old Friday 21st February 2020, 04:14   #53
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I recently read Ken Rockwell's 'editorial' on a used Leica Trinovid 10x40, that folks have been commenting on.

https://www.kenrockwell.com/leica/tr...40.htm#compare

Ken Rockwell is amusing, but irritating as well. He doesn't even list an eye relief spec., instead just blithely announcing "Not a lot, but plenty for normal use!" I did find a spec for it: 12mm. That's awful, for me at least.

He also seems unaware that an Uppendahl is a roof prism, proclaiming that 'roof and porro prisms just can't compare' to the superior characteristics of the Uppendahl...

One more nugget from Mr. Rockwell:
Close focus on the old Trinovid: About 7.5 meters (25 feet), measured.

"If you need to get closer, then why are you using binoculars? Closer focus distances are a sham."

I guess he'd fit right in here at the binocular forum! ;-)

I also found a Leica catalog from 2017. According to that catalog, they are no longer using Uppendahl prisms in the Geovid either, having replaced them with Perger-Porro prisms.
https://nimax-img.de/Produktdownload..._EN_rz_low.pdf (page 34)

I don't expect we'll be seeing Uppendahl prisms in any new binoculars any time soon. Another prism bites the dust.

-Bill
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Old Friday 21st February 2020, 05:40   #54
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I also found a Leica catalog from 2017. According to that catalog, they are no longer using Uppendahl prisms in the Geovid either, having replaced them with Perger-Porro prisms.
No comment on Rockwell ...

Unfortunately Leica purchased the rights to the Perger prism from Andreas Perger AFAIK. So unless they decide to use the Perger prism in other binoculars, there won't be a binocular with this very interesting prism that offers all the advantages of a porro prism in a smaller package.

That's a shame.

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Old Friday 21st February 2020, 06:18   #55
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Hi Chosun, Thanks for offering up some concrete thoughts. Far more solid than my own! I was conducting a Gedanken experiment to see how far it can go, even fantasizing of a subscription kickstarter project, to hire Kamakura to build an 'edition' of bins to an 'idealized' spec. Or use other means to convince one of the major players to produce a 'retro' custom bin... This is not a practical venture... but interesting.

Meanwhile, you're already thinking specifics..

Standardization. You've addressed an element of it with regard to thinking about prisms, but ahead of that might be agreeing on a format... 7x, 8x, 10x, - 30, 32, 35, 40 42, 50...

Here's a collection of random observations in response:


Prisms:
I was leaning towards Porro, partially because I bow to the experience and expertise around here that I lack. In addition, the simplicity of manufacture might offer an advantage in terms of cost and the opportunity for less things to go wrong...

Plenty of good minds here, but consensus on anything is not a hallmark of this place. I figured on just digging up what I could find on prisms to learn for myself the whats and the whys. There's so many folks who could probably address many issues you bring up straight away, and be done with it.

A few more things to chew on:
You've probably read up on Henry Link's experience with his 8x56 Zeiss Victory FL..achieving a certain optical nirvana by walking between the aberrational raindrops, so to speak...accepting the flaws of manufacture (Zeiss!) and simply reducing the amount by increasing the size of the exit pupil relative to the entrance pupil. A novel approach with a minor drawback: the bins need to be bigger for it to work. Trying to leverage that advantage into another format leaves me thinking: 6x42, 7x50... ?

Moreover, reading a range of comments over the last few months, including Henry's own well done textbook example of an optical evaluation of a binocular for one of the recent Kowa BD xII deluxe turbo something or other...

https://www.birdforum.net/showthread.php?t=384387

Even Henry points out that the wide resolution deficit between the Kowa and his reference standard, the Nikon EII, is probably not noticeable until one puts the binocular on a tripod. Basically, that handheld binoculars can get away with lower resolution, because it can't be detected by most people when used that way..

Listening to Chuck Hill try to tweaze out the optical differences between an Ultravid Silverline and a Noctivid in an entire day out birding, or Canip doing something similar in a Leica shop, comparing the new Trinovid to some others, supports Henry's assertion to some extent, and also tells me that this whole dialogue is exactly what Bill Cook accuses us of doing repeatedly: Stacking BB's and hair splitting, And I think he's right.

Doesn't mean its not fun, but there are a lot of practical realities to chew on...

First off, the current, excellent by most standards, performance of the top roofs is an indisputable benchmark. One can buy an existing product that is THAT GOOD. Drawback: costly.

Also on the market are products like the Habicht and the Canon IS lines, considered top optical performers by many, AND less expensive. Drawback: ergonomic dinosaurs, poor eye relief, narrow FOV on some models.

Then suppose we try to shoehorn Henry's optical strategies into this cauldron of variables...
What is the threshold of decreasing the exit pupil/entrance pupil ratio of performance advantage? I don't have a clue.

Simple example:
I've got a Carton 'Adlerblick' 7x50 binocular that I've owned for over 20 years. Orion sold them, advertised as long eye relief for glasses. Its got a 7 fov, weighs about 785 grams, and close focus is in the 7 meter ballpark. There's an
example of a 50mm Porro that has the weight of a portly 8x42 roof...A viable chassis perhaps to start with?

What if we bump up the specs to 8.25 FOV, close focus 3 meters, maintain eye relief @ 18mm, then how much bigger and heavier would it be? How much more glass does it take to widen, and better correct the field? What if we bump magnification to 8x50?
Would a 6.25 mm exit pupil be enough to grant the improved performance relative to a 7mm EP in daylight viewing? Inquiring minds want to know! (or not!)

Light Transmission: I'll go with a 3% minimum threshold for visual detection, based on some rational consensus on earlier threads I've read. Some of the top roofs are in the 94% range. Even the 7x42 Habicht at reportedly 96% won't likely be a detectable difference, just a numerical advantage on paper. If we aim for a wider field, we're probably adding more glass, which drops the transmission regardless of the prism size...

Attempting to fine tune color balance, flatten the curve, is an interesting endeavor. I have no idea which part of the system would make the most impact on it... maybe coatings.

Cat herding, BB stacking... consensus of format... consensus of anything...

That's all I got for today. I appreciate your interest and energy on the topic.

-Bill
Bill, most of this comes down to the esoteric art of cat herding and geomancy !

I have my own thoughts on a lot of it, but of necessity they have to remain proprietary until my remuneration contracts are signed and the money is in the bank !

We don't have to worry about BB stacking or practical limits - just shoot for the stars ...... the very last thing this poor beleaguered world needs is more medicore junk !

I'm going to need 8.5x mag, 150m Fov, 18mm ER, and a secret sauce objective size. IR prisms will of course be de Rigeur - though not the wings out Porro I type, nor the physically long A-K's. Weight will be less than 2/3rd kilo which will entail reams of biomimmicry design and a BOM chock full of unobtanium.






Chosun

P.S. I think Dennis might actually BE Ken Rockwell, and not Howard Stern after all ..... !

Last edited by Chosun Juan : Friday 21st February 2020 at 06:25. Reason: I think my phone is either possessed, or under the control of the NSA !
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Old Friday 21st February 2020, 07:35   #56
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Hi Bill (post #53),

Quote:
Originally Posted by wdc View Post
. . .
I also found a Leica catalog from 2017. According to that catalog, they are no longer using Uppendahl prisms in the Geovid either, having replaced them with Perger-Porro prisms.
https://nimax-img.de/Produktdownload..._EN_rz_low.pdf (page 34)
. . .
-Bill
To clarify about the Geovids:
- the 3rd Generation open bridge HD's (pages 52 to 55 of the catalogue) use Perger prisms, but
- the 2nd Gen one piece bridge R's (page 56) use Uppendahl prisms

Or more precisely, there's no indication to the contrary in relation to the 2nd Gen Geovids, either in this or any other Leica published information that I'm aware of


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Old Friday 21st February 2020, 15:03   #57
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Bill, most of this comes down to the esoteric art of cat herding and geomancy !

I have my own thoughts on a lot of it, but of necessity they have to remain proprietary until my remuneration contracts are signed and the money is in the bank !

We don't have to worry about BB stacking or practical limits - just shoot for the stars ...... the very last thing this poor beleaguered world needs is more medicore junk !

I'm going to need 8.5x mag, 150m Fov, 18mm ER, and a secret sauce objective size. IR prisms will of course be de Rigeur - though not the wings out Porro I type, nor the physically long A-K's. Weight will be less than 2/3rd kilo which will entail reams of biomimmicry design and a BOM chock full of unobtanium.

Chosun

P.S. I think Dennis might actually BE Ken Rockwell, and not Howard Stern after all ..... !
Chosun, I rather think mention of the unobtanium BOM(b) is an indiscreet disclosure.
I do respect your proprietary interests, but please, please do share the recipe for your secret objective sauce. I know Ina Garten would if she had one...

As for the shock jock journalism, 6 degrees of separation, Birdforum conspiracy mashup, my current theory is that Rico is Dennis' Italian uncle, and Ken Rockwell is his step dad... Dennis' real father is the LEICAMAN, the shadowy figure that Ken takes so much pleasure in belittling. I think this explains everything! Mere conjecture on my part, though , and furthermore, the DNA test has not come back from the lab yet. ;-)

The elevator is out at work, so I've found myself going Uppendahl the stairs all morning, which gives me an appetite. I think I will have a hamPerger for lunch, followed by a generous slice of Pechan pie...I feel sorry for those Porro folks whose inhibitions don't allow them to enjoy such things. Perhaps its just a phase they're going through. Take my friend Abbe- The other day I knocked on her door. "Koenig", she said. I walked in and the place was lousy with binoculars.

Where have you been?

Prism, she said, reflecting internally.

Happy Friday



-Bill

Last edited by wdc : Friday 21st February 2020 at 20:40.
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Old Friday 21st February 2020, 15:06   #58
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Hi Bill (post #53),



To clarify about the Geovids:
- the 3rd Generation open bridge HD's (pages 52 to 55 of the catalogue) use Perger prisms, but
- the 2nd Gen one piece bridge R's (page 56) use Uppendahl prisms

Or more precisely, there's no indication to the contrary in relation to the 2nd Gen Geovids, either in this or any other Leica published information that I'm aware of


John
Hi John, Thanks for setting the record straight. I looked at it more carefully, and you're right, they don't tell you in the catalog. A listing for the Geovid-R on Optics Planet specifies 'Roof', which indicates Uppendahl.
Also, the body contours of the Perger-porro Geovids are quite different than the Geovid-R.

-Bill

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Old Friday 21st February 2020, 17:38   #59
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Chosun, I rather think mention of the unobtanium BOM(b) is an indiscreet disclosure.
I do respect your proprietary interests, but please, please do share the recipe for your secret objective sauce. I know Ina Garten would if she had one...

As for the shock jock journalism, 6 degrees of separation, Birdforum conspiracy mashup, my current theory is that Rico is Dennis' Italian uncle, and Ken Rockwell is his step dad... Dennis' real father is the LEICAMAN, the shadowy figure that Ken takes so much pleasure in belittling. I think this explains everything! Mere conjecture on my part, though , and furthermore, the DNA test has not come back from the lab yet. ;-)

The elevator is out at work so I find myself going Uppendahl the stairs all morning, which gives me an appetite. I think I will have a hamPerger for lunch, followed by a generous slice of Pechan pie...I feel sorry for those Porro folks whose inhibitions don't allow them to enjoy such things. Perhaps its just a phase they're going through. Take my friend Abbe- The other day I knocked on her door. "Koenig", she said. I walked in and the place was lousy with binoculars.

Where have you been?

Prism, she said, reflecting internally.

Happy Friday



-Bill
Bill - lol - I direct your focus to the Mexican Wave circulating clockwise amongst your audience. Round of applause !

Given the results of the binocular format survey so far being nearly evenly split between full and mid size, I think we can objectively direct our gaze to the those ballparks ...... we can leave the biro-tubed compacts, and Hairy-chesTed big eyes out of the equation for now.







Chosun

P.S. I hope Abbe- is adjusting well to life on the outside. :)
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Old Friday 21st February 2020, 18:28   #60
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P.S. I hope Abbe- is adjusting well to life on the outside. :)
Abbe- is doing fine. 2 air-to-glass surfaces are enough for her. She's been through plenty of Schmidt-....


So....32 -42? No 50?
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Old Friday 21st February 2020, 18:38   #61
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'...

As for the shock jock journalism, 6 degrees of separation, Birdforum conspiracy mashup, my current theory is that Rico is Dennis' Italian uncle, and Ken Rockwell is his step dad... Dennis' real father is the LEICAMAN, the shadowy figure that Ken takes so much pleasure in belittling. I think this explains everything! Mere conjecture on my part, though , and furthermore, the DNA test has not come back from the lab yet. ;-)
...

-Bill
That pretty well describes it. Thanks for the chuckle. You don't need any of the prism systems to erect the image you portray.
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Old Saturday 22nd February 2020, 00:23   #62
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Abbe- is doing fine. 2 air-to-glass surfaces are enough for her. She's been through plenty of Schmidt-....


So....32 -42? No 50?
Lol ! that's good to see.

Well those are the main ballparks anyway ..... !
50ish is the outer limit, but we'll leave carrying the real big eyes bricks to the true bino aficionados




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Old Saturday 22nd February 2020, 03:31   #63
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..................... and I sure don't plan to join Brock and Joe down in the rabbit hole discussing irrelevant or fanciful objective designs or glass types "we know nothing about". -- Henry Link

Chosun, In examining your .sig, which I think you've had ever since I've been a member, it seems like a rather prescient statement with regard to this thread, wouldn't you say?... ;-)

Are we not just digging a new rabbit hole? Maybe we're doing a bit more homework...

I see it primarily as a learning opportunity, with no expectations. Bicycles can be 'built up' ,component by component, on a specified frame. Isn't that the service a company like Kamakura essentially offers? I do not expect miracles in this process...

Uppendahl, no (only one source, unless its all NOS, and no longer in production), Perger-Porro, nope (Leica patent rights)...
Abbe-? S-P? Porro? Only 3 options left.

Birding tomorrow! No more speculative optics fantasies for at least 24 hours...

-Bill

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Old Saturday 22nd February 2020, 20:56   #64
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I really do not think prisms are desirable optical components.
Lenses have symmetry, so they are relatively easy to align correctly and hold firmly.
Prisms are asymmetrical objects intolerant of misalignment. They have no place in the optical train imho, because mistakes happen all to readily and bumps are a fact of life.
At worst, the extra lens for an all lens system needs to be a lot faster. to keep the length down. That seems doable, considering what is possible in the camera lens world.
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Old Saturday 22nd February 2020, 22:17   #65
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Hi Etudiant,

Camera lenses don't need to erect the images.
The image is upside down.
It is only needed for the viewfinder on SLRs.
On rangefinder cameras the viewfinders are Galilean reversed optics usually.

Relay lenses for binoculars make for a long instrument.

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Old Saturday 22nd February 2020, 23:06   #66
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I really do not think prisms are desirable optical components.
Lenses have symmetry, so they are relatively easy to align correctly and hold firmly.
Prisms are asymmetrical objects intolerant of misalignment. They have no place in the optical train imho, because mistakes happen all to readily and bumps are a fact of life.
At worst, the extra lens for an all lens system needs to be a lot faster. to keep the length down. That seems doable, considering what is possible in the camera lens world.
Interesting ideas. What has kept an all lens binocular from happening in the last 100 years or so? Especially considering the development of camera lenses in that time? Is it only image erecting issues, length of the optical train, or something else? AFAIK, SLR film cameras all used an erecting prism in the viewfinder, so the lens was providing an inverted image onto the film.

As for faster lenses, my only concern there would be an increase in CA.

-Bill
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Old Sunday 23rd February 2020, 00:57   #67
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Hi Etudiant,

Camera lenses don't need to erect the images.
The image is upside down.
It is only needed for the viewfinder on SLRs.
On rangefinder cameras the viewfinders are Galilean reversed optics usually.

Relay lenses for binoculars make for a long instrument.

Regards,
B.
The thought is that a fast relay lens will address the length issue.
One sees lots of rifle scopes that are not excessively long, so I'm hopeful it is practicable.
I accept that CA for a fast relay lens is an issue potentially.
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Old Sunday 23rd February 2020, 15:04   #68
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There are quite a few SLRs that use mirrors for the viewfinder rather than prisms.

Some such as the Wrayflex use just one mirror for a reversed image but very nice look and reduced height.
Others use two mirrors for a correct image but increased height.

Some cameras use mirrors to fold the light path onto the image for a very slim package.

I would think that high end mirrors could be used in binoculars, but few use these.

There are erect image eyepieces but these usually have small fields.

B.

P.S.
The Ucaflex from about 1950 uses a mirror and prism for a periscope effect.
It has a reduced height.
A friend had one, but it was too expensive for me to buy.
They are rather rare, but I don't know how much they cost nowadays.

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Old Monday 24th February 2020, 01:01   #69
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There are quite a few SLRs that use mirrors for the viewfinder rather than prisms.

There are erect image eyepieces but these usually have small fields.
The Ucaflex from about 1950 uses a mirror and prism for a periscope effect.
It has a reduced height.
A friend had one, but it was too expensive for me to buy.
They are rather rare, but I don't know how much they cost nowadays.
The issue is not the prisms per se, but rather all the non axi-symmetric elements, whatever they may be.
The hope is to create a much cheaper and more robust device.
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Old Tuesday 25th February 2020, 00:45   #70
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One sees lots of rifle scopes that are not excessively long, so I'm hopeful it is practicable.
I too believe it is practical to make binoculars with lens-based erectors. There are premium-class riflescopes made by a [formerly] premium-class manufacturer which are only 30cm long:

https://www.schmidtundbender.de/en/p...tra-short.html
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Old Tuesday 25th February 2020, 07:04   #71
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Omid, post 70,
30 cm is at the long side for my theater binocular, I will be arrested probably when I try to use them in the theater.
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Old Tuesday 25th February 2020, 08:33   #72
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Omid, post 70,
30 cm is at the long side for my theater binocular, I will be arrested probably when I try to use them in the theater.
Gijs van Ginkel
LOL !




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Old Thursday 5th March 2020, 23:31   #73
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Prism-less Binoculars?

Why not dispense with prisms and just use lenses? Back at post #32 etudiant raised this question

By chance I’ve just come across a similar discussion in Cloudy Nights from March 2019: https://www.cloudynights.com/topic/6...-scope-design/

Particularly see post #14 by the always informative Rich V, quoting from Greivenkamp and Steed
In brief, prism-less binoculars, even with very small objectives:
- were very long in use (see the image from G & S), and
- if designed to collapse for carry, there were considerable technical difficulties

In relation to the latter, perhaps akin to achieving a quality zoom binocular today?


John


And even with updated cosmetics, would you buy one? . . .
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Old Friday 6th March 2020, 03:45   #74
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Why not dispense with prisms and just use lenses? Back at post #32 etudiant raised this question

By chance I’ve just come across a similar discussion in Cloudy Nights from March 2019: https://www.cloudynights.com/topic/6...-scope-design/

Particularly see post #14 by the always informative Rich V, quoting from Greivenkamp and Steed
In brief, prism-less binoculars, even with very small objectives:
- were very long in use (see the image from G & S), and
- if designed to collapse for carry, there were considerable technical difficulties

In relation to the latter, perhaps akin to achieving a quality zoom binocular today?


John


And even with updated cosmetics, would you buy one? . . .
Thanks for posting these pictures John. As to the question of a contemporary version, they don't seem physically practical at all unless the objective size was quite small. Perhaps a handheld mount in the manner of a modified stock might be the best way to use them, but then how would the focuser be accessed? The last question is whether the 2 lenses offer any advantage over a prism in terms of light transmission, CA, or field distortion. If not, then there may be no clear rationalization for modernizing that format.

Maybe weight is less with lens than prism? Binocular spotting scope on a mount?

They do have a steam punk vibe, so might find favor in that culture, for goth bird watching festivals (bats!)

-Bill

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Old Friday 6th March 2020, 06:42   #75
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Hi Bill,

Now that you mention it, . . . they just might very well be the perfect choice for some of those folks on Bat Forum (‘the forum for wild bats and bating’)!


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