With binoculars, how do I make the images align?

[overlord (Charles)]

All my life I close one eye cos there is two images?!

Pls heeeeeeeelp.

focusing didn't seem to work. It's like its beyond focus or something.

BTW i have 20:20 vision.

[jjjnettie (Jeanette)]

The only thing I can think of is that you have the oculars spread too far apart. The ones I'm using at the moment only need to be opened up about half an inch.

[andyc (Andy)]

Is this the case with many different pairs of binoculars, or just one? If you have the same problem with lots of different pairs of binos, then I've no idea what the problem is. Ever had a lazy eye or one eye much more dominant than the other (probably not, if you have 20:20)? Even then, I'm not sure that would cause the same issue?

If it's just the one pair of binoculars that you've had for years, it may be that the barrels are not correctly aligned with each other (ie they've been bumped or otherwised damaged). I had an old pair like that, was a nightmare trying to align them and get them to focus correctly. In that case, try someone else's binoculars, or go to a shop and try a new pair out, and see if that's any better!

[mental4astro (Alexander)]

It could be one of two things, one mechanical and the other "personal".

1, Your binos may not be collimated, or aligned, properly. Binos are aligned to give parallel images by manipulating the prisims inside the housing. Porro type binos can be recollimated by manipulating the collimation screws on the body that contains the prisims. If these screws are not seen it may be that they are under the rubber coating of the housing. It isn't a difficult process, but it is time consuming.

This is a good article on collimating binoculars on Cloudy Nights.

A common thing to knock the alignment out of binos is dropping them or sharp knocks. It happens too all brands, and it can be fixed, unless the collimation screws are not accessible or just not there.

2, By "personal" I mean it is the way you actually look through them. With my 11X70 binos, if I focus my eyes on the image I see two. If I focus my eyes on the background, my eyes are focused at infinity and I see one image! It is a technique change that takes a little getting used to. I also find my eyes relax and using the binos are less difficult on my eyes. Just a little getting used to the new technique.

I suggest to first try the technique change first - It's easier & quicker than recollimating.

Mental.

[The Mekon (John Briggs)]

Binoculars are also collimated by turning eccentric rings that mount the objectives. This is the way better class binoculars are aligned. I have done this (using a bright star) with some success on a pair I purchased on ebay. Cheap binoculars do not have these eccentric rings, and often there is no means of aligning them at all.

[dannat (Daniel)]

Are the binos you have aligned? Have you had them checked or got someone else to look thru them? If you want to meet in melb send me a pm & when I'm in melb I can check them for you (the bins not your eyes)

[ZeroID (Brent)]

A pair I bought for parts to fix my own Bins where just badly aligned. The thread on one of the objective assemblies was cross threaded. I fixed them instead with a few bits from my old bins because they were (other than the broken focusser screw) better than mine.
They are now my current best astro 12 x 50 Zeniths with some light sheilds on the front. They have a flatter field than my 10 x 50 Olympus bins.
Took a bit of CRC and some determined pressure to free the jammed thread but once I got it right it screwed in perfectly. Check to see if there is a wee gap (< 1mm) between the body and the front objective lens assembly on one side. That was my clue as what was wrong.

[Poita (Peter)]

As mentioned, this can be a problem with the binoculars themselves.

If it happens on all binoculars, then it might be your vision, or as Alex mentioned, your viewing technique.

When getting a standard vision test done, convergence isn't always tested, it is easy to test for though, and any optometrist can tell you within a few seconds if you have an issue.

http://www.mayoclinic.com/health/con...-and-diagnosis

http://nacd.org/journal/article11.php

[Chris.B (Christopher)]

Roger formally of BATSC in Melbourne. (I think is now in Bintel Sydney)
Was a master of fixing this issue. He gave the ASV a talk on it. He used a rubber mallet. Charged I think $40. As he said You work out which side is out and wack accordingly. Prism drops back into place and all fixed.