20x80 binocular balancing

[RT65CB-SWL]

Hi all. 

I have a problem when using my 20x80 binoculars. I am left eye dominant when using a telescope.

When using my binoculars on a celestial target, I tend to see two of the object, i.e. one in each eyepiece. When using on terrestrial targets during the day time I do not see it. I have read this article (see below) from www.nipon-scope.com...

 

...and was wandering if this will eliminate the problem, or should I get my eyes re-tested and explain it to the ophthalmologist/optometrist/optician? ...or should I get the binoculars collimated?

 

   

[Stargazer McCabe]

Philip I’d venture the binoculars need collimating. The brain has the ability to take miscollimated daytime images and make sense of them I believe as it “knows what it should be seeing”...

On celestial point source targets it processes what it sees “as seen”. Therefore if an anticipated single point source target shows as a double, I’d start your investigation with the binoculars themselves.

The other observations you make may all help along the lines of “marginal gains”. But I think the likely area of greatest improvement will be the binoculars themselves. 

Although I am no expert, I write based on similar experiences 

[Mr niall]

Yep I had exactly the same thing in my 15x70s - looked perfect in the day (or so I thought!) but didnt stand up under scrutiny at night.

A good way to check in the day is to open and close each eye alternately. The image should stay in more or less exactly the same place (with a little left/right shift of course so use something as far away as possible)

If its jumping position from eye to eye then they're probably out.

The silver lining to this cloud is that if they are slightly off then you will notice an incredible difference in depth and clarity - especially in the day time - when you get them right.

collimating bins isnt that challenging, theres loads of videos, its literally just the turn of a screw in most cases.

[BinocularSky]

The night sky, as you have discovered, is a far stiffer test of binoculars than is any daytime scene. If the binocular is still under warranty, return it.

I have an objective tube from one of these binoculars (intending to make an 80mm finder). I've just dismantled it and cannot see how adjusting either of the rings in the diagram would make a blind bit of difference to the lens (if someone can, please tell me!).

 

However, if you pull back the rubber on a prism housing where I've indicated, you should see a tiny screw hole (may need glue-removal). Use a small flat screwdriver and it will move the image in the direction you are screwing it.  Use Polaris. If you defocus one image, so it is a blob, this will stop your eyes trying to merge them. Tweak the screws until the focused star ends up in the middle of the blob. It'll probably only be correct for your IPD.

 

 

HTH, but feel free to ask more if you need to.

[PeterW]

See how many Jupiter’s/mars/Venus you have.... much easier test of poor collimation. If other binoculars give you a single image  then these ones are at fault. If all bins give you double then maybe it’s you. You can get bins recillimatednrkr around £30, or you can try various online DIY options, though you would be very lucky to do it as good.

hope you get it fixed.

 

PEter

[Captain Scarlet]

With Porro-prism binoculars the prisms themselves are often not very securely held in place, a sharp knock can be enough to shift a prism in its housing, resulting in an off-centre view at best. Actually dropping them can obviously be far worse. I bought a pair of new Opticron 10x70s recently which had clearly been dropped. But, as Peter says, easily fixed for not too much.

Cheers, Magnus.