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binoculars that can accommodate -10 correction? (1 Viewer)

pat mitchel

Active member
One of the posters on the cloudy nights binocular forum asked whether there are any binocs that can be used when a user has -10 (very nearsighted) correction. Seeing as no binoc sites specify how much infocus they have, how is one to know? I still have an early pair of eagle optics 8x32 ranger/platinum that I got with a large rebates (good glass) that surprised when first used without my glasses (-3.75 correction) and found I couldn't focus at infinity. Fortunately now that I have aged and my correction has weakened a bit, they are now (barely) useful under night skies... Thoughts???????? Regards, Pat
 

Binastro

Well-known member
Minolta 8x23 AF binocular, I think,
I'll have a look later.

Also maybe some Porros.

A binocular repairer could alter, say a minus 7 binocular, to reach minus 10 dioptres.
But others may not be able to use it.

Regards,
B.
 

Pinewood

New York correspondent
United States
Hello Pat,

My correction used to be -7.5, but it is now -4.5, so I can use some binoculars without my glasses. However, I find this adequate only in daytime. At night, my astigmatism becomes far more evident. I hope that your eyes are fairly well matched. Mine differ by only a half dioptre.

Really old individual focussing binoculars did accommodate my -7.5 correction. I am writing of 1917-1934 military binoculars. The Swiss Army binoculars of those years were meant to accommodate even rather myopic reservists. As I recall my 7x42 Zeiss Dialyt classic, just managed to allow me to come to infinity. I have a Leica BA, which almost focusses at infinity without my specs: it works at 100m but not on Mars. Try either one to see if it works for you, but do not buy one on my speculation. I consider both binoculars only a little behind the times.

One remedy, which I would not recommend on an expensive binocular, is to get a plastic negative lens, of the proper dioptre or even weaker, and glue it to the binocular at the objectives. Even worse would be to glue it to the objective itself. The former would mar the surface, the latter would entail permanent damage.

Another remedy is to get an optical technician to customise the focussing. Then you gain focussing at infinity but lose some near focussing. Perhaps a first rate manufacturer would do it on a new binocular or allow a special order. I did just that when I sent an eighty year old binocular to a technician for a thorough cleaning, adjustment and collimation. Before the adjustment it barely focussed at infinity; now it has some focussing to spare.

Stay safe,
Arthur Pinewood :hi:
 

WJC

Well-known member
One of the posters on the cloudy nights binocular forum asked whether there are any binocs that can be used when a user has -10 (very nearsighted) correction. Seeing as no binoc sites specify how much infocus they have, how is one to know? I still have an early pair of eagle optics 8x32 ranger/platinum that I got with a large rebates (good glass) that surprised when first used without my glasses (-3.75 correction) and found I couldn't focus at infinity. Fortunately now that I have aged and my correction has weakened a bit, they are now (barely) useful under night skies... Thoughts???????? Regards, Pat

Hi, Pat,

Although I see you have 15 posts under your belt, I don't think I've seen you here before.

The objective(s) need to be recessed. I'm not set up for that (and, slowing down my efforts, may never be, again) Cory has done that many times. Has nobody on CN suggested that to you? :cat:

Bill
 

opisska

Jan Ebr
Poland
Hello Pat,

My correction used to be -7.5, but it is now -4.5, so I can use some binoculars without my glasses. However, I find this adequate only in daytime. At night, my astigmatism becomes far more evident. I hope that your eyes are fairly well matched. Mine differ by only a half dioptre.

Some eyepieces used in astronomical telescopes accept correctors at the eye-facing side that make them work for people with astigmatism. I just wondered upon reading your post whether something like that might exists for binoculars?
 

Patudo

Well-known member
From the nature-observation point of view, your friend would be well advised to wear glasses/spectacles that provide the required compensation, and use a binocular that has sufficient eye-relief to be used while wearing glasses/spectacles. Without glasses you won't find many birds, or much other stuff, to look at if your prescription is -10; and even if you're very practiced with whipping away your glasses and bringing the binoculars to your eyes, there will still be many instances where you're still not quite fast enough.

Increasing focus further beyond infinity can be done by technicians with the right equipment; but if your friend has astigmatism as well as nearsightness, it won't correct for that. Glasses are the better solution. Having said that, I did get one of my old binoculars adjusted, but try to use it only in situations where I don't anticipate needing to find a bird by eye first.
 

pat mitchel

Active member
Good Afternoon; The gent simply posted a question, then later wrote that he had a -10 correction. I had thoughts of simply buying soem old porros that have a lot of adjustability in the lens cells and move them back. I also though of getting the cheapest mail order optometrist correct prescription glasses and make small insert that might be silicone glued to the eyepieces. I seem to recall dioptrix that screwed into telescope eyepieces but that was above what I'd spend for a pair of binocs. Are roof binocs commonly as adjustable internally as the classic porros of the last century? Just looking at the options that might be available- a mental exercise. Out of curiosity, why don't makers commonly list the limits of correction in specs? Many don't list the diopter limits to the right eyepiece. Regards, Pat
 

Binastro

Well-known member
I can't find the instructions for the Minolta 8x23 Autofocus binocular, but from memory it may be minus 13 to plus 5 dioptres. This is tentative unless confirmed.

Beechers Mirage binoculars and Maven may provide solutions for minus 10 dioptre correction.

B.

P.S.
Looking at an online instruction leaflet it seems that the dioptre adjustment range of the Minolta 8x23 Autofocus binocular is minus 12 dioptres to plus 4 dioptres.

I haven't seen a report of someone with minus 10 dioptres correction using one.
 
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