Binocular collimation and eyepieces question

[Mark Wagner]

I'd had a pair of Miyauchi 100mm binoculars tucked away for years and now feel like using them.  So a couple questions someone out there might have answers to.

They appear to be out of collimation.  I there are a few services out there that can do the job, one was Texas Nautical years ago, and they nicely referred a company. I've written them, but wonder if someone local has the know how.

Second, they came with I believe 20mm and 37mm oculars.  But I only have the lower power.  And they are not 1.25" which would have been nice, they are smaller.  Has anyone built eyepieces?  I think with 3D printing now, design and manufacture would be easy if one had/obtained the correct lenses.

Maybe the low power will be sufficient, just exploring.

Thanks,

Mark

[Richard Navarrete]

https://mountainoptics.com/

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[John Pierce]

My 71 yr old eyeballs are out of collimation, I see double in binocs in low light conditions, so my solution is to use a monocular.  its also more compact and easier to carry.   I found quite a nice 8x42 ED monocular from an offbrand, the optics are as good as any I've seen, reasonably wide field of view, and great eye relief for my eyeglasses.

Opticron Explorer WA ED-R 8x42 Monocular

[Mark Wagner]

Funny, John.  My eyes are still collimated, or at least I think so.  They're just seem red-shifted.

I just measured (eyeballing) the 20X Miyauchi eyepiece at a 35mm barrel, and an old 1.25" Kellner at 31mm, so if I can laser cut a few 2mm wide acrylic rings at 35mm OD, I may be able to buy a pair of eyepieces and jury-rig them to work.  I'd assume at low power like this they don't need to be great quality, just good, and will work?

I found Siebert Optics, whose e-mail addresses now bounce, but they have info on Miyauchi.  Says the 100mm pair I have are 500mm f/l.  And that the 20X pair of eyepieces I have are 25mm.  Does that make any sense to you (or others)?  I'd like to figure out what mm eyepieces I'd need to replicate or get near the 37X of the originals.  Any help would, well, help.

There are several places that seem to offer collimation, I've written.

Thanks anyone else (Richard) for the help!

Mar

On 11/16/2025 12:38, John Pierce wrote:

My 71 yr old eyeballs are out of collimation, I see double in binocs in low light conditions, so my solution is to use a monocular.  its also more compact and easier to carry.   I found quite a nice 8x42 ED monocular from an offbrand, the optics are as good as any I've seen, reasonably wide field of view, and great eye relief for my eyeglasses.

Opticron Explorer WA ED-R 8x42 Monocular

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Mark

[John Pierce]

On Sun, Nov 16, 2025 at 12:47 PM Mark Wagner <itsmar...@gmail.com> wrote:

Funny, John.  My eyes are still collimated, or at least I think so.  They're just seem red-shifted.

I just measured (eyeballing) the 20X Miyauchi eyepiece at a 35mm barrel, and an old 1.25" Kellner at 31mm, so if I can laser cut a few 2mm wide acrylic rings at 35mm OD, I may be able to buy a pair of eyepieces and jury-rig them to work.  I'd assume at low power like this they don't need to be great quality, just good, and will work?

I found Siebert Optics, whose e-mail addresses now bounce, but they have info on Miyauchi.  Says the 100mm pair I have are 500mm f/l.  And that the 20X pair of eyepieces I have are 25mm.  Does that make any sense to you (or others)?  I'd like to figure out what mm eyepieces I'd need to replicate or get near the 37X of the originals.  Any help would, well, help

500/37 == 13.5mm FL eyepiece.