Double Vision Hi I have an Oberwerk 12 x 36 x 70 Zoom binoculars, fully muli coated. They have just recently developed double vision : I see the viewed image twice over. This happens even though the lenses are fully centred. This problem disappears whenever I close either eye. Any suggested solutions much appreciated. Kieran

Hello, do you mean that lens coating fell off? I hope not, but who can say when these Night vision monoculars and binoculars are soley manufactured in Russia. Hint: auction it on eBay. US Night Vision Optics will not warranty the lens coating, sorry. GB...stewbison.

The prisms have shifted inside of the binoculars. This is not an easy job as you have to make corrections to the angle of the prisms for leaning field and collimation. Two suggestions:
1. If they are under warranty take them to a repair agent.
2. If you want to do it yourself, there are instructions on the web about how to go about effecting a collimation. Too long to go into detail here.

Less beer ?

Try grabbing the binoculars in both hands and twisting the body in the opposite direction of the double vision until the images coincide.

Your question is listed under "Zhumell Oberwerk 45 25x100 Astronomy binoculars". If these are what you have then they're an extremely high end expensive specialist item and will need professional realignment. I'm assuming that if you do own a pair of these then you're knowledgeable enough to have done all you can to adjust them correctly.

I suspect that you have a regular pair of 10x50 or similar binoculars, with a centre focus wheel and hinges. If this is the case then try to wiggle one of the eyepieces back and forth: if you can easily move it and the other eyepiece remains steady then you have a broken hinge. This is a very common fault especially if your binos have been dropped or if they've been stored in their case upside down (i.e.standing on the eyepieces).

A broken hinge is normally a write-off as there is rarely sufficient area to us epoxy glue on and the metal used is not usually suited to being brazed. Even when the hinge can be repaired it's normally permanently misaligned.

Either resign yourself to using one half of your binoculars or buy a new pair. In the UK LIDL regularly sell a pair of Meade 10x50 binos of excellent quality for just over £10 and that's only a little more than a bottle of epoxy resin glue costs. You may be interested to know that one of the world's most successful supernova spotters does so in his back garden in the UK using just half a pair of old 7x50 binos.

take it into an outdoor shop and they can check the mirror alignment, seems that it may have "altered' itself

I was having a double vision problem with my Barska 10-30X50 zoom, 195FT/100YDS binoculars. One image was always higher than the other. This was tolerable at low zoom, but was further aggravated the more I zoomed in. I found that I could grasp both barrels and twist them in opposite directions (one side up, the other side down) and force the two images to merge--but that was a strain and an unpleasant viewing experience. As an experiment, while looking through the binoculars, I grasped the far end of the right barrel and twisted it on its axis. Nothing happened at first, but after a certain amount of resistance it began to rotate independently of the body. Lo and behold, this shifted the barrel's axis, and the image for that eye moved vertically! I turned it until the two images merged, and now I'm thrilled to say that the problem is solved! I don't have a clue if this would work on any other brand or model, but it's worth a try!

I'm assuming you have set the dioptre correctly for your eyes.

Normally this is caused by a collimation error when one (or both) prisms move. This can be by a small amount.

Your going to have to take them in for service/repair to fix this as is not a DIY problem. (Unless of course you have a collimator lying around)

We can align yur binoculars for your for 25-30.00 plus 5.00 to ship back to you. Some units have handy set screws to make adjustments from outside the unit. Call me, wwwbinocularservice.com
Art

The distance between the centers of the eyepieces of your binocular must be the same as the distance between your pupils. This distance is adjusted as follows: 1. Focus on a distant object. 2. Pivot the two halves of your binocular farther or closer apart until you can see a single unobstructed, circular field of view. Make sure to focus on a distant object when you do this because when you focus on a close object you always see two slightly overlapping circular fields. Your binocular may have a scale on the top, between the eyepieces, to help you remember this setting.