Why not more DIY “big eyes”?

[4th_point]

I just saw this IG post from AA

 

[4090Sharps]

I just saw this IG post from AA


View attachment 628279

I’m looking at my straight Razor 13-39x56 right now wondering if I could rig up something similar. It has smaller eyepieces than the STC from the looks of it.

 

[4090Sharps]

Screengrabbed from AA Instagram

He doesn’t hang around! Looks really cool, I imagine this will be fantastically light and useful for some segment of the marketView attachment 626446View attachment 626447

More from IG.

These look like the best blend of weight, bulk, and performance for where/how I like to hunt and glass. Like a supercharged set of SLC 15x56 binoculars.

 

[SikaSeeker]

 

[SikaSeeker]

Banana for scale , two Kowa TSN824 I’m turning into a set. They just about work with my eyes, bracket isn’t made yet but lining them up the view is incredible.

The paint is a pain to remove but necessary, I may repaint with something suitable.

 

[Wyo_hntr]

Why do you have to remove the paint?

 

[4090Sharps]

Banana for scale , two Kowa TSN824 I’m turning into a set. They just about work with my eyes, bracket isn’t made yet but lining them up the view is incredible.

The paint is a pain to remove but necessary, I may repaint with something suitable.
View attachment 631594

Do you have drawings for what your bracket will look like? I’m still thinking about buying a second 13-39x56 Razor to make my own bracket like @Hatchet Jack did.

 

[SikaSeeker]

The Kowa paint on these scopes is a nightmare, it fails becomes sticky and gets everywhere. If you’re lucky to be in the US kowa seem willing to repaint with few qualms. I saw a set of 822(I think) for sale on US FB marketplace as I was looking for 21/20x kowa eyepieces. They had an elaborate bracket that had screw adjustment. When I get the bracket I’ll post more pics, expecting around start of Feb24.

 

[ozyclint]

I hope kifaru's latest pack comes with a big eyes shelf.

 

[4090Sharps]

Do you have drawings for what your bracket will look like? I’m still thinking about buying a second 13-39x56 Razor to make my own bracket like @Hatchet Jack did.

I took some measurements on my 13-39x56 Razor that I have on hand. Max diameter is on the focus ring at 2.800". Accounting for clearance to turn (unless I'm missing something), that would leave a pair mini Razors too wide for budget big eyes. Oh well! Maybe a pair of STCs will work for my eyes.

 

[Valsport]

Any recommendations on how to rig up two GR 30x60's? They've got 1/4-20 female thread bases, seems like an arca rail, clamps and stand-off's would make it pretty easy? Looks like about 2.25" CTC min spacing on the eyepieces.

 

[SikaSeeker]

Astronomy retailers make mounting plates for side by side use with cameras etc, used by astrophotographers I think. Losmandy make the fancy gear in that world. There are lots of budget options, I’d considered going that route.

 

[4090Sharps]

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

I threw this info into a table for sake of comparison using the weights I could find on the web + weights from Adams Adapters. Feel free to add any info, make corrections, etc. Added the Swarovski SLC 15x56 as a sort of baseline and common frame of reference.

Brand	Size/Model	Single Obj Area (cm2)	Double Obj Area (cm2)	Bracket Weight (oz)	~ Total Weight	Magnification	Max Exit Pupil (mm)	Min Exit Pupil (mm)
Kowa	TSN-664	34.21​	68.42​	22​	6lb 12oz	30, 20-60x	3.3​	1.1​
Kowa	TSN-774	46.57​	93.14​	38​	9lb 12oz	25-60x	3.1​	1.3​
Kowa	Highlander	52.81​	105.62​	-	13lb 10oz	32x	2.6​	2.6​
Kowa	TSN-884	60.82​	121.64​	40​	10lb 12oz	25-60x	4.4​	1.5​
Swarovski	65 BTX	33.18​	-	-	4lb 13oz	30x / 51x	2.2​	1.3​
Swarovski	85 BTX	56.75​	-	-	5lb 8oz	30x / 51x	2.9​	1.7​
Swarovski	95 BTX	70.88​	-	-	6lb 1oz	35x / 59.5x	2.7​	1.6​
Swarovski	115 BTX	103.87​	-	-	7lb 8oz	35x / 59.5x	3.1​	1.9​
Swarovski	ATS 65 big eyes	33.18​	66.36​	26​	7lb 9oz	25-50x	2.6​	1.3​
Swarovski	ATS 80 big eyes	50.27​	100.54​	21​	8lb 5oz	25-50x	3.2​	1.6​
Swarovski	STC	24.63​	49.26​	20 (est.)	5lb 8oz	17-40x	3.3​	1.4​
Swarovski	SLC 15x56	24.63​	49.26​	-	2lb 10oz	15x	3.7​	3.7​

 

[4090Sharps]

I took some measurements on my 13-39x56 Razor that I have on hand. Max diameter is on the focus ring at 2.800". Accounting for clearance to turn (unless I'm missing something), that would leave a pair mini Razors too wide for budget big eyes. Oh well! Maybe a pair of STCs will work for my eyes.

I think my IPD may be too narrow for the dual STC setup as well. The OD of my new-to-me STC is right around 2.530". For me, it's too close to buy without trying in person first.

 

[SikaSeeker]

Min IPD for STC is 2.5” acc to Adam, this may be reduced removing eyecups (i think).

A last resort would be getting a surgeon to take a die grinder to your nose bridge

 

[4090Sharps]

Min IPD for STC is 2.5” acc to Adam, this may be reduced removing eyecups (i think).

A last resort would be getting a surgeon to take a die grinder to your nose bridge

I wonder if that's a close estimate on his part. Close enough for those of us who don't have closely spaced eyes. The OD of the magnification ring is where I got the 2.530" then you'll need just a bit of clearance for adjustment.

My IPD is 2.520"--Might need to install a spacer between my eyes.

 

[Brian Fahs]

On the twin kowa 664s removing the eyecups makes for a much more comfortable glassing experience. Ipd be damned, your nose gets in the way.

 

[itsgobe]

I just saw this IG post from AA


View attachment 628279

I’m so stoked for the STC setup!

 

[6.5x284]

I’m so stoked for the STC setup!

STC adapters live on the site 1/12/24 at noon! Got mine!


Sent from my iPhone using Tapatalk

 

[4090Sharps]

STC adapters live on the site 1/12/24 at noon! Got mine!


Sent from my iPhone using Tapatalk

My narrow-set eyes and I are green with envy.