Why not more DIY “big eyes”?

[4th_point]

I made my own bracket for Kowa 66s out of aluminum using a grinder, hole saw, sawzall, thread tappers and some pure redneck ingenuity. Been going strong for 4 years and they’ve ridden a lot of miles in my pack. They are my favorite optic I own. I’ve glassed a brown elk shed at a confirmed 1.4 miles with them and glassed my coues this year at 1700 yds mid day in the shade. No way I’m doing that without 30 power. And At 7 lbs I don’t mind packing them a few miles.

Man I would love to see that setup if you'd be so kind to post a picture.

Jason

PS - I was so impressed with a TSN-604 for the weight that I bought a second and am thinking about making a mounting plate.

 

[SikaSeeker]

I saw Hatchett Jacks setup in another forum, looks really beefy plate aluminium. Unsure exactly how it works and if it provides 3axis collimation vs “conditional alignment”.

3 axis basically means anyone can use the binos whereas conditional isn’t as accurate but are aligned for your personal eyes.

 

[4th_point]

I saw Hatchett Jacks setup in another forum, looks really beefy plate aluminium. Unsure exactly how it works and if it provides 3axis collimation vs “conditional alignment”.

3 axis basically means anyone can use the binos whereas conditional isn’t as accurate but are aligned for your personal eyes.

I found pictures at another forum. Thanks.

 

[BBob]

I’d like to see some guys do field tests with various brackets , testing how well they stay collimated.

Not much functional difference between the Wells and the Adams. Both adjusted and locked down seem to do fairly well. Mine is a Wells and it's never come out once collimated. I treat it fairly carefully though but no different than a BTX or how friends treat the BTX or any optic for that matter. Some guys including Wells himself leave one side loose so you can rotate one optic. Wells said the IPD can change slightly between low mag and high mag and he slightly adjusted his between different mags. I didn't find that with mine and locked both sides down. The collimation can be slightly different between low mag to high mag. Mine differs but only slightly. I collimated mine at 25x and locked it down there because that's what I use near 99% of the time. Wells was the opposite and said he did his personal at 50x.

 

[chutinlead]

My dad picked up a set of these when we stumbled across them.

20 X 80 WIDE ANGLE BINOCULARS

<p><span style="font-family: Arial, Helvetica, sans-serif; font-size: small;">Great design and low Surplus Shed price!!! These are unused in the original box with case, neckstrap, instructions, and front and rear lens caps. This has a very sturdy tripod bracket. Rubber hand grips, center focus...

www.surplusshed.com

They are....interesting.

Just pony up and shell out for a non portable set like this:

https://www.bhphotovideo.com/c/product/651215-REG/Kowa_BL_8H_NC_Landscope_20x80_Binocular.html

 

[dtrkyman]

I have been thinking about a second Kowa 774 and making a bracket, have an engineer friend who would probably make something pretty awesome!

 

[Hatchet Jack]

I saw Hatchett Jacks setup in another forum, looks really beefy plate aluminium. Unsure exactly how it works and if it provides 3axis collimation vs “conditional alignment”.

3 axis basically means anyone can use the binos whereas conditional isn’t as accurate but are aligned for your personal eyes.

I’m not sure what all that means but they are comfortable to glass with for hours. After I built them I’ve had 3 buddies who looked through them all bought setups of their own so it worked for them pretty good too. I really didn’t overthink it and maybe I just got lucky and they worked out. They really are spectacular optics. And yeah it’s a fairly beefy set up if I were to do it again I would probably make the bottom plate a little thinner but They are still right around 7 lbs total so well worth the weight on certain hunts

 

[Sierra Hunter]

How many manufacturers of the plates are there?

 

[BBob]

How many manufacturers of the plates are there?

Out west the only two I know of currently are Wells Sports in the Prescott Valley, AZ and AdamsAdapters in San Manuel, AZ. Montour Rifles used to make some. Swarovski sold a set for awhile but no idea who's bracket they used. There were quite a few back east but I don't know who they were or are.

 

[SikaSeeker]

3 axis alignment in binoculars is both barrels aligned in 3 axis AND aligned with hinge. It takes fair amount of skill plus equipment to do 100% accurately. It’s not a big deal as far as I can tell if you do conditional alignment unless you’re extremely sensitive/have “bad” eyes.

Friend of mine runs machine shop for quarry rock equipment so my biggest issue would be convincing him to do it, if it’s worth the time etc as they’re usually frantically busy.

 

[BBob]

Being that big eyes are somewhat of a specialty glass I see no need to make them with a hinge or anything to change the IPD. It only adds complexity and the chance for a collimation change. I've seen brackets where one optic slides horizontally to make IPD changes. All it does is add weight and complexity. Wells and Adams just trimmed that away and made a minimal and a more solid device. In several years I haven't had the need to have anyone look through mine and change the IPD because they have their own big optic. If I glass something I just call it out and they look at it with their optic. If they want to see it through my optic they can look through one scope and see it just fine. IMO these things are best used as specialty glass and not as a universal "binocular". If you want something universal I'd buy the BTX and be done with it. That said in all my years glassing we here as a group almost never ever look through someone else's optic, we just call it out and they look at it themselves through their own.

 

[SikaSeeker]

The bracket approach is ideal for this use case absolutely. I’d been reading a US Navy optical man’s ranting about collimating errors hence why that was on my mind. Would like to see pics of Wells adapter if possible. I’ve got one Kowa 664 body and 2x 30 x EPs so just need another body before I can look at bracket & maybe making one myself. I’m based in U.K. and Europe so unless I can convince a buddy to take one home it’s not feasible for me.

 

[BBob]

The bracket approach is ideal for this use case absolutely. I’d been reading a US Navy optical man’s ranting about collimating errors hence why that was on my mind. Would like to see pics of Wells adapter if possible. I’ve got one Kowa 664 body and 2x 30 x EPs so just need another body before I can look at bracket & maybe making one myself. I’m based in U.K. and Europe so unless I can convince a buddy to take one home it’s not feasible for me.

Wells Sports as far as I know only makes his bracket for Swaro STS 65's. Wells builds his on the side and makes his $$$ elsewhere so I get the feeling he's not too worried about selling many. Kind of a locals word of mouth market. There have been a couple for sale on this forum so you could do a search to find and see the Wells here. If you want a bracket for Kowa or Swaro 80's you'll have to go to AdamsAdapters. Adams has an easily found website so you can see his.

 

[Hatchet Jack]

The ipd is adjusted by the scope body rotating, no adjustments on the bracket need to be made to adjust ipd.

 

[SikaSeeker]

Benny Wells adapter pictures in this thread , look similar to Adams Adapters

WTS - Twin Swarovski STS Spotters ("Big Eyes")

Looking to sell my Swaro Big Eyes / Twin Spotters. Have loved every second of owning them but need to fund a new project and want someone else to enjoy using them. Used them in Ol’ Mexico to verify size of bucks from a long way off. What I dig about them is that you don’t have to strain your...

rokslide.com

 

[4th_point]

I understand that IPD is adjusted by rotating the scope bodies, but how are the optical axes aligned with the Wells and Adam's? I don't see any adjustments and the front ring appears fixed. I don't see an eccentric either.

 

[SikaSeeker]

Have chance to purchase BTX85mm but have heard Kowa 664s are better?

Has anyone compared BTX 95 or 115 to the Kowa 664s?

BTX 115 vs 132(66x2) Kowa’s in terms of light gathering. Surely they wouldn’t beat Swarovski?

 

[4th_point]

Have chance to purchase BTX85mm but have heard Kowa 664s are better?

Has anyone compared BTX 95 or 115 to the Kowa 664s?

BTX 115 vs 132(66x2) Kowa’s in terms of light gathering. Surely they wouldn’t beat Swarovski?

I'm curious about the twin 664 vs. BTX as well.

I have read that you need the 95 or 115 to match the twin 664 for light transmission. I forgot where. Maybe at MM or CW forums.

I also wonder how much 3D effect you get with the twin 664. Or is that only at close range.

 

[SikaSeeker]

It’s the total area of the glass that is the determinant factor. 115mm will resolve more detail than two 66mm. Did some sums of popular combinations of big eyes and this should give a rough guide of what to expect note BTX despite the aperture real estate will be dimmer vs bino scopes / big eyes. It’s not the full story which is a bit more complex. With big eyes “binocular summation factor” comes into play and some estimate this can have the effect of up to 1.6x perceived magnification/brightness etc. BTX doesn’t benefit from this phenomenon as much due to the beam splitter.

Area of glass (pi x (radius x radius) ) in centimetres squared

Kowa scopes

66mm scope = 34.21 Big eye 2x 66mm =68.42

77mm scope = 46.57 Big eye 2x 77mm = 93.14

82mm scope = 52.81. Highlander = 105.62

88mm scope = 60.82 big eye 2x88mm = 121.64

Swarovski

85BTX = 56.75

95 BTX = 70.88

115 BTX = 103.87
ATS 65 big eyes = 66.36

ATS 80 big eyes = 100.54

 

[Brian Fahs]

It’s the total area of the glass that is the determinant factor. 115mm will resolve more detail than two 66mm. Did some sums of popular combinations of big eyes and this should give a rough guide of what to expect note BTX despite the aperture real estate will be dimmer vs bino scopes / big eyes. It’s not the full story which is a bit more complex. With big eyes “binocular summation factor” comes into play and some estimate this can have the effect of up to 1.6x perceived magnification/brightness etc. BTX doesn’t benefit from this phenomenon as much due to the beam splitter.

Area of glass (pi x (radius x radius) ) in centimetres squared

Kowa scopes

66mm scope = 34.21 Big eye 2x 66mm =68.42

77mm scope = 46.57 Big eye 2x 77mm = 93.14

82mm scope = 52.81. Highlander = 105.62

88mm scope = 60.82 big eye 2x88mm = 121.64

Swarovski

85BTX = 56.75

95 BTX = 70.88

115 BTX = 103.87
ATS 65 big eyes = 66.36

ATS 80 big eyes = 100.54

Nice post.