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Corrector lens for a binocular (2 Viewers)

kabsetz

Well-known member
I have always preferred to use binoculars without glasses on, but for a few years now my left eye has deteriorated with increasing astigmatism and some other aberrations to a point where it is compromising the view more than I'm willing to accept.
When I had new glasses made this summer, I asked my optician to make me a corrector lens to my left eye prescription to be mounted over the left tube eyelens under the rubber eyecup.

It works better than I had dared to hope. Here is a pic
 

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kabsetz

Well-known member
In the picture, rubber eyecup is removed. With it on it looks like the right ep. Attachment is with three tiny pieces of double-sided tape used for attaching eyeglass lenses to a grinding machine for shaping to fit frames. Lens is circular and ground to a diameter 0,5 mm smaller than eyecup inner diameter.
 

Hauksen

Forum member
Hi Kimmo,

I have always preferred to use binoculars without glasses on, but for a few years now my left eye has deteriorated with increasing astigmatism and some other aberrations to a point where it is compromising the view more than I'm willing to accept.
When I had new glasses made this summer, I asked my optician to make me a corrector lens to my left eye prescription to be mounted over the left tube eyelens under the rubber eyecup.

It works better than I had dared to hope. Here is a pic

Highly interesting, thanks for sharing! I presume the lens always remains in a defined orientation (in rotation)?

Regards,

Henning
 

exup

Well-known member
United Kingdom
I have always preferred to use binoculars without glasses on, but for a few years now my left eye has deteriorated with increasing astigmatism and some other aberrations to a point where it is compromising the view more than I'm willing to accept.
When I had new glasses made this summer, I asked my optician to make me a corrector lens to my left eye prescription to be mounted over the left tube eyelens under the rubber eyecup.

It works better than I had dared to hope. Here is a pic
Interesting option.

Here is a Dioptrx used too: Eye relief insufficient for glasses - Page 2 - Binoculars - Cloudy Nights
 

kabsetz

Well-known member
Henning,

You can see in the picture a marking made on the lens for rotational orientation. It is filed to make it permanent, but accentuated with a red felt-tip pen. We chose not to have dioptric correction for my lens, since there's not much dioptric difference between my eyes, and because my left eye produces a larger image scale to my brain than my right eye, and adding diopter correction to this lens would have exacerbated that. But for those who run out of diopter range on their binoculars, that would be worthwhile.

I get significantly more relaxed and sharper views with this lens. Although my right eye, which I use for telescope viewing, is better, I might get a corrector lens for its prescription also to use on the scope.

- Kimmo
 

Tringa45

Well-known member
Europe
Kimmo,

Borosilicate and multicoated?
According to this TeleVue chart DIOPTRX™ you would profit at 4 mm exit pupil if you needed a cylindrical correction above 0,5 dioptres.

John
 

kabsetz

Well-known member
John,
My Lens is the same Zeiss I have in my glasses, but single strength and without the + correction I need for glasses as the binocular focusing takes care of this. Same multi coatings and Lotutec Zeiss has for their best glasses. A side benefit from not having dioptric correction is that the thinner lens adds less CA.

B.
I'm not in the least surprised that someone has done this before. What surprises me is that it is not done more. My optician, who has made a lot of glasses for hunters and outdoors people had never made one before.

- Kimmo
 

kimmik

Well-known member
United States
I like the idea of customising binoculars to your eyes, could take it further with custom shape eyecups, would you have any thoughts on this?
 

kabsetz

Well-known member
Another advantage of having eyesight deficiencies corrected with an add-on lens on the binocular is that field of view is not compromised and eye placement is not critical like it is with eyeglasses. Also, as this lens is not a progressive, the entire field of view is as sharp as the binocular optics allow, with no weirdness coming from glasses.

A potential problem I foresee is condensation forming between the eyelens and the corrector lens, but I will have to wait until fall-winter to see if this happens.
 

kabsetz

Well-known member
Kimmik,

On eyecup customisation I have no specific ideas, except that in my experience with anything too well customised and closely fitting, fogging of the eyepieces quickly becomes a problem. Therefore something like a loose hood tends to work better.

- Kimmo
 

elkcub

Silicon Valley, California
United States
Hi Kimmo,

Great idea! I had a similar one back in 2005 (see post #1). Maybe the industry will listen ... but don't count on it. :)

Since I'm forced to wear eyeglasses, Canon IS binoculars do not provide sufficient eye relief, but prescription corrector lenses would do the trick.

Regards,
Ed
 

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