35 replies to this topic

[jrazz]

I recently (yesterday) got a fun astronomical device to play with:

 

 

This is a 50mm straight through binocular without erecting prisms meaning it's just 2, 50mm telescopes bonded together with a hinge and 2 collimating barrels. 

It's a hoot and immensely enjoyable to play with. As you can see above I've been using them with a pair of ES82, 8.8mm eyepieces which essentially make a 23x50 binocular with an 82° AFOV (roughly 3.6° FOV). Totally fun.

 

However, AFOV fever has struck and I'm *eyeing* a pair of Astro-Tech XWA 7mm for an even more extreme view. I would have limited myself to a 13mm eyepiece but those are too wide for my use and the resultant IPD would be above 65mm.

 

So hence my question. If anyone can take a caliper o their AT XWA 7mm and tell me what the maximum barrel diameter is I would be really grateful. Also, do you have any recommendations on other really wide eyepieces to play with? I don't think I want to spend on Naglers for this but what about 13mm UWAs? Those look pretty neat and much less expensive.

[Starman1]

I recently (yesterday) got a fun astronomical device to play with:



This is a 50mm straight through binocular without erecting prisms meaning it's just 2, 50mm telescopes bonded together with a hinge and 2 collimating barrels.
It's a hoot and immensely enjoyable to play with. As you can see above I've been using them with a pair of ES82, 8.8mm eyepieces which essentially make a 23x50 binocular with an 82° AFOV (roughly 3.6° FOV). Totally fun.

However, AFOV fever has struck and I'm *eyeing* a pair of Astro-Tech XWA 7mm for an even more extreme view. I would have limited myself to a 13mm eyepiece but those are too wide for my use and the resultant IPD would be above 65mm.


So hence my question. If anyone can take a caliper o their AT XWA 7mm and tell me what the maximum barrel diameter is I would be really grateful. Also, do you have any recommendations on other really wide eyepieces to play with? I don't think I want to spend on Naglers for this but what about 13mm UWAs? Those look pretty neat and much less expensive.

7mm is 58mm in o.d.

[A Y]

The shorter Ethoses (8, 6, 4.7, 3.7) are between 53.3mm and 56mm, but they are spendy.

[SeattleScott]

I recently (yesterday) got a fun astronomical device to play with:

 

 

 

This is a 50mm straight through binocular without erecting prisms meaning it's just 2, 50mm telescopes bonded together with a hinge and 2 collimating barrels. 

It's a hoot and immensely enjoyable to play with. As you can see above I've been using them with a pair of ES82, 8.8mm eyepieces which essentially make a 23x50 binocular with an 82° AFOV (roughly 3.6° FOV). Totally fun.

 

However, AFOV fever has struck and I'm *eyeing* a pair of Astro-Tech XWA 7mm for an even more extreme view. I would have limited myself to a 13mm eyepiece but those are too wide for my use and the resultant IPD would be above 65mm.

 

 

So hence my question. If anyone can take a caliper o their AT XWA 7mm and tell me what the maximum barrel diameter is I would be really grateful. Also, do you have any recommendations on other really wide eyepieces to play with? I don't think I want to spend on Naglers for this but what about 13mm UWAs? Those look pretty neat and much less expensive.

If performance matters, and it might not for this application, the 13 UWA is relatively new and not a lot of reviews, no bench tests by Ernest. I have been able to glean that the edge correction is better than the not so hot 16 UWA but not as good as the pretty good 10 UWA. The binoculars are likely a fast F ratio, so a 13 UWA likely won't be quite sharp to the edge, given people have reported minor edge softness in F5 Dobs. Again, might be fine for this application.

[jrazz]

The focal length is 200mm so yeah, f/4.

 

I think the UAW are a perfect match for them but the XWA seems so nifty...

 

Oooof, decisions.

[scout]

My wrists hurt just looking at that.

[MisterDan]

The focal length is 200mm so yeah, f/4.

 

I think the UAW are a perfect match for them but the XWA seems so nifty...

 

Oooof, decisions.

Methinks that's t-shirt worthy. 

[TOMDEY]

Saaaay, jrazz... can you tell me how to order this thing (the bino, not the eyepieces). I visited the site and got confused regarding how to order. I love playing around with new idea stuff and am inclined to order it, get it, and use my existing eyepiece pairs to see what I can see. My IPD is a generous 71mm (thanks, God!), so it seems almost sinful for me to waste this opportunity. Thanks!    Tom

 

We joined the navy to see the world
And what did we see? We saw the sea
We saw the Pacific and the Atlantic
But the Atlantic isn't romantic
And the Pacific isn't what it's cracked up to be ~

[jrazz]

Happy to. The best option is to email Kyoei directly and ask. They answer very quickly and are awesome to deal with. email is: shopmaster@kyoei-osaka.jp

 

The other option is to go to the site:

https://www.kyoei-os...llaBino-50.html

 

Click on "add to cart". 

Next part is important. Go to the cart. There's a small drop down that allows you to choose between Japanese and English. Pick English and the cart will change to export mode and from there there are explanations.

 

Again, I cannot say enough nice things about Kyoei. 

If you do order this, please let us know what you think in the thread over on the Binoculars forum. I'd love to read your opinion!

[SeattleScott]

The focal length is 200mm so yeah, f/4.

I think the UAW are a perfect match for them but the XWA seems so nifty...

Oooof, decisions.

The trick with the XWAs will be fitting your nose between them. Easier for some than others. Oh, and the weight of course. Hand holding it steady could be a trick.

I’m sure the UWA won’t be perfect to the edge at F4 but you probably don’t care too much about that for this application.

[jrazz]

TBH the UWA are probably perfect for this application. I mean try finding 82° AFOV 12x50 binoculars... Go ahead, I'll wait.

 

I know that at $100 a shot these are a no-brainer and my brain is saying go for it.... I will probably end up getting some UWAs and the 7 XWA just because I can't help it. These are FUN!

[ubernator]

Does it have a tripod adapter hole at the front of the hinge?

[jrazz]

Yup. And a cheap, 10$ Amazon adapter fits wonderfully.

 

It is horribly unbalanced though. The eyepieces are by far the heaviest part and even swept back, the adapter is too far forward. It's light though so that might not be an issue.

[sevenofnine]

Maybe this kind of tripod adapter would work better? 

 

https://www.amazon.c...aps,738&sr=8-15.

[cimar]

I use a pair of 10mm UWA eyepieces with my BTs. This is my favorite and mist used pair with the BT 100.

[areyoukiddingme]

With 200mm focal length, I'm going to guess there's substantial field curvature. It may be that going beyond ~60 or so degrees is going to show too much field out of focus.

[jrazz]

Does it have a tripod adapter hole at the front of the hinge?

[Houdini]

The trick with the XWAs will be fitting your nose between them. 

That's the easy part.

I'm lucky to have a large IPD of 70 mm, which makes it possible to use most Ethos in a binoscope, but don't manage to see the 100° field with both eyes simultaneously.

It appears that to observe a 100° field with one eye I tilt my head in a way that I cannot achieve for both eyes simultaneously (maybe it's just a matter of eye relief).

So even if my IPD is big enough and I can fit my nose between the eyepieces, I still cannot go significantly beyond 80° with two eyes.

[SeattleScott]

That's the easy part.
I'm lucky to have a large IPD of 70 mm, which makes it possible to use most Ethos in a binoscope, but don't manage to see the 100° field with both eyes simultaneously.
It appears that to observe a 100° field with one eye I tilt my head in a way that I cannot achieve for both eyes simultaneously (maybe it's just a matter of eye relief).
So even if my IPD is big enough and I can fit my nose between the eyepieces, I still cannot go significantly beyond 80° with two eyes.

Yes, owls would love binoviewing. They can move their eyes independently.

[Starman1]

That's the easy part.

I'm lucky to have a large IPD of 70 mm, which makes it possible to use most Ethos in a binoscope, but don't manage to see the 100° field with both eyes simultaneously.

It appears that to observe a 100° field with one eye I tilt my head in a way that I cannot achieve for both eyes simultaneously (maybe it's just a matter of eye relief).

So even if my IPD is big enough and I can fit my nose between the eyepieces, I still cannot go significantly beyond 80° with two eyes.

This is why binoculars with apparent fields larger than 65° are rare.

If you look right and left to the edge of the field, simply averting the eye suffices for up to about 68°.

Beyond that, you have to roll your head a little to look directly at the edge, and doing so, with two eyepieces, lifts one eye away from the exit pupil on that side.

It's why I do not advise binoviewer or binoscope observers to use eyepieces wider than 70°.

It will be possible to see the outer fields of ultrawide eyepieces with 2 eyes using peripheral vision, but not direct vision.

[f18dad]

This is why binoculars with apparent fields larger than 65° are rare.

If you look right and left to the edge of the field, simply averting the eye suffices for up to about 68°.

Beyond that, you have to roll your head a little to look directly at the edge, and doing so, with two eyepieces, lifts one eye away from the exit pupil on that side.

It's why I do not advise binoviewer or binoscope observers to use eyepieces wider than 70°.

It will be possible to see the outer fields of ultrawide eyepieces with 2 eyes using peripheral vision, but not direct vision.

 

Unless you have googly eyes! 

[jrazz]

I have often made that argument - that you really can't see the entire field.

I still think so. For doubles I usually pick the TPL and am very happy with the AFOV but the experience of a really wide view is different. 

 

Aaaanyway, I ended up finding a used Stellarvue Optimus 9mm which should work. I'll let you know how it turns out.  

[eyeoftexas]

Jordan: I have a few questions about these, if you don’t mind:

 

Are the views “brighter” compared to roughly equivalent binoculars?  In your set-up in Post #1 the exit pupil is ~2.1mm.  But since all light from a 50mm objective goes to each eye, does that make the image brighter?

 

It appears from your calculations that the 50mm binoculars have a focal length of 202mm.  Is that correct?

 

What kind of glass is used in these?  How is the CA on bright objects, etc.?  Is it ED glass?

 

Thanks for any answers you can provide.

[jrazz]

Jordan: I have a few questions about these, if you don’t mind:

 

Are the views “brighter” compared to roughly equivalent binoculars?  In your set-up in Post #1 the exit pupil is ~2.1mm.  But since all light from a 50mm objective goes to each eye, does that make the image brighter?

 

It appears from your calculations that the 50mm binoculars have a focal length of 202mm.  Is that correct?

 

What kind of glass is used in these?  How is the CA on bright objects, etc.?  Is it ED glass?

 

Thanks for any answers you can provide.

Always happy to talk about these

 

I would suggest going to the thread on the Binoculars forum: https://www.cloudyni...iece-binocular/

That thread has more information but since you asked here...

 

I don't think "brighter" is the right word. The Nikon Astrolux 18x70 is definitely "brighter" but I attribute that to the bigger exit pupil. I do think the contrast is very very good on these. It manifests as them being very sharp as compared to other, similar binoculars. On doubles like STF 2276 or STF 2449 they outperform the Astrolux and match the APM 34x80 - a much bigger binocular despite the handicap of the smaller aperture.

 

Yes, the focal length is 200mm making them f/4.

 

According to: http://kasai-trading...llabino50e.html

They are "f/4 doublet achromat objective lenses". In practice the CA isn't very intrusive. Sure, looking at rooftops with a bright sky beyond shows some lateral CA but at a level that seems to be on par with very high quality binoculars that call themselves "APO". At night I have not seen a lot of CA. At least it doesn't seem to bother me. I did expect a f/4 achromat to be full of astigmatism and color but TBH, under the night sky and with the ES82 8.8mm this doesn't seem to be much of an issue. No, it's not an APO but I don't expect it to be and therefore it's not an issue. Makes you think if we are overly critical on our refractors...

 

TL;DR; these are super fun and refreshing to use. They are not intended to compete with high end refractors or binocular telescopes but they are super light and perform way better than they have any right to.

[jesse 3]

Since it is f4, I am thinking of making night vision binoculars.

How’s focuser travel range?

I like to use Televue 40mm Plossl which requires longer focuser travel. With PVS14, it will be long. At 5x magnification, it may be hand held friendly. It would be a big optical improvement over 3x magnifier I am using.