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Owl Eyes 2.3x40 Binoculars

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#1 asaint



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Posted 27 May 2008 - 08:22 AM

Owl Eyes 2.3 x 40

#2 ZachK


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Posted 27 May 2008 - 08:55 AM

Sounds like the kind of thing one might wish to wear as a pair of glasses or the like.

#3 EdZ


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Posted 27 May 2008 - 09:23 AM

They provide extremely low power, wide field views and a huge 17mm exit pupil. I had the binoculars out last summer and noted that I could fit the entire Teapot of Sagittarius within the field of view. In contrast to the 28-degree field listed on the binocular's rear bezel, I estimate that the binoculars provide about a 17-degree field.

Interesting comment about the actual Tfov, would indicate the Afov of these eyepieces is much closer to 40° than the stated 64°, similar to what I have seen in some very inexpensive children's binoculars.

Due to human eye pupil limitations that max out at about 7mm, the 17mm exit pupil can never be fully utilized by the human eye for all the light it delviers. While you'll get that large filed of view experience, the most aperture you ever get to use out of this binocular is about 16mm, or perhaps 18mm if you have eye pupils that open to 8mm.


#4 StarStuff1



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Posted 27 May 2008 - 01:03 PM

The identical pair I have give a true field of approximately 23°, not as wide as advertised but also much wider than the author's experience. Maybe I have the eye lenses closer to my eyes. Other than this the author's experiences seem identical to mine.

I have compared my Russian binos with the newer version from Blue Planet Optics. This latest iteration has better coatings, improved baffling and more contrast. Not a huge difference but enough to tell.

The idea of a wrist strap is good. I will add one to mine. Thanks!

#5 ph2


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Posted 27 May 2008 - 01:35 PM

I have a 2.3x40 binocular purchased last year. It is not made in the 1990s, but part of a new batch made for Kasai Trading in Japan. The specifications are probable similar to the older model reviewed here.

In my binocular, I can see Vega and Deneb in the same field of view without too much effort. They are separated by 23.85 degrees in the sky and that is a lot wider than only 17-degrees.

The sharpness of the stars across the field of view center-to-edge in my 2.3x40 is comparable to the view in my Nikon Action 10x50 and 7x35 binoculars. That is IMHO an acceptable quality for a $130 price-tag.

In the 2.3x40, I can see stars down to magnitude 7, when the naked eye limiting magnitude is about 5 - a gain closer to 2 than 1 magnitude. When focused, the stars do actually appear sharper in the 2.3x40 than the naked eye view (Hmm, I think I need glasses).

I’m quite satisfied with the performance of this little binocular.

#6 dougspeterson



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Posted 28 May 2008 - 04:44 PM

Sounds like the kind of thing one might wish to wear as a pair of glasses or the like.

Check out Beecher Mirage Glasses on the web, or ebay used. I have an old pair, only one side good unfortunately due to coating loss. They have this weird, dual field characteristic where the magnified field appears inside your peripheral vision. I am suprised more astro-people do not check these out. Watch out, there are cheapo magnifying eyeglass wannabes that are no good.

#7 Glassthrower


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Posted 28 May 2008 - 08:26 PM

I've been curious about these oddball widefield binoculars for some time now.

Hats off to Aaron on the review. :waytogo:

Doug - it's funny you mention the Beecher Mirage "glasses". I have bid on two pairs of those on eBay over the last couple of years, and I always get outbid. I did some reading up on them a while back, and it appears that they (and glasses like them) were designed for people with vision problems - there was even a website with an article discussing the do's and don'ts of DRIVING while wearing glasses such as these! (For the record - don't!)

If I ever run across the right deal on one, I'll pick it up. :)

#8 Aaron McNeely

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Posted 31 May 2008 - 08:47 PM

Kasai Trading in Japan sells these type of binoculars:


They also offer a goggle assembly in which you can insert a pair of 2.3x40 binos. I had considered mentioning this in my article but didn't. This might be a fun item to have.

#9 GlennLeDrew


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Posted 23 June 2008 - 10:32 PM

In order to get my eyes closer to the eye lenses, which is all-important for getting the maximum field out of a Galilean optical system, I un-screwed the rear eyepiece disks (those with the holes you look through). Now I get close to the stated field of view of 28 degrees (but it does require getting my corneas rather close to the lenses.)

Also, I used flat black paint to cover the ground glass edges of the eye lenses so as to greatly reduce scattered light getting into my eyes.

#10 JKoelman


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Posted 01 July 2013 - 11:22 AM

A international team of researchers have created a folded Galilean design yielding an ultra flat optical train (physical length 1.17 mm), thereby reducing a binocular to a pair of contact lenses. And yes, this contact lens binocular is switchable between 1x and 2.8x power. Unfortunately, the light gathering power is fairly limited... (And I guess it will take a while before you can get these taylor-made for your eyes..)

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