Barska 8x42 out of collimation

[medwatt]

Hello,

I was offered a Barska 8x42 binoculers for a negligible price that I could not resist. I tried it and it was out of collimation. However when used in the configuration shown in the image, it was perfect. Image was very sharp and the focusing was tight. I had to buy it. So, is there a way to adjust the collimation ? For example, when its not in the configuration shown, I start seeing shadows, not double images. I am not an expert in binoculers so is there something I can do ?

[ronin]

Do you wear glasses?

If so wind the rubber eye cups down, as otherwise your eyes are at the wrong position.

If you do not wear glasses the the eye cups need to be wound out as in the image.

[medwatt]

Do you wear glasses?

If so wind the rubber eye cups down, as otherwise your eyes are at the wrong position.

If you do not wear glasses the the eye cups need to be wound out as in the image.

Actually, I forgot to mention this in my original post. I have to set the eye cups as they are shown on the binoculars to be able to get an undistutbed view. Here's my observations:

1. When the eyecups are fully up, there're shadows (black regions) only when the binocular is opened to its extreme. There's no double image, just blackness and a small patch of light.

2. When the eyecups are down, no matter how much closer I bring the two barrels, I still get the shadows or blackness.

If this is a collimation issue, there doesn't seem to be double images. I just see shadows or blackness.

[Ruud]

It's pupil distance.

By bending the binos you change the pupil distance. There's only one distance that fits your eye distance. You seem to have found that distance.

If you make the pupil distance too wide or narrow, you get the shadows you mention.

In short: you have no collimation problem.

[Ruud]

Your number 2 above probably has to do with eye relief.

Adjust the height of the eyecups so that you see the whole field of the binoculars. The height required differs a lot between those who need to wear glasses and those who do not.

[ronin]

As Ruud says you move the 2 halves to get the seperation that matches your eyes, if you do not wear glasses then the eye cups are as shown - wound out - if you wear glasses they are wound in, that gives the eye relief position.

You do not, it would seem, have a collimation problem.

[medwatt]

As Ruud says you move the 2 halves to get the seperation that matches your eyes, if you do not wear glasses then the eye cups are as shown - wound out - if you wear glasses they are wound in, that gives the eye relief position.

You do not, it would seem, have a collimation problem.

So my binoculers don't have any problems ? I shocked !!!  I also had the Skymaster 15x70 and one of the issues I had was that I had double images at all barrel separations (forgot the term) except at one value.

So last question. Is the issue of shadows a common thing for any roof prism binocular ?

[Ruud]

Your 8x42's sound OK so far.

The 15x70's had a collimation problem. The tubes were out of alignment and pointed in different directions.

How is the view through the 8x42's, with the right pupil distance and the best eye cup height? They are nice and small so you can take them everywhere. I hope you get to use them a lot.

[medwatt]

BTW, Whats the term used to describe when the binoculars are collimated just at one configuation. I've forgotten the term.

Its 00:40 here. Happy New Year !! :smiley:

[Peter Drew]

I think the term is orthoganal. The light from the binocular exits through the small exit pupil at the eyepiece, if your eye is not exactly lined up with this then shadowing occurs, as others have said the binocular hinge and the adjustable eyecaps enable you to do this.