Barr and Stroud Binoculars (1 Viewer)

Advice please, I've just purchased a pair of Barr and Stroud 10x42 Series 4 Binoculars and have detected a variance in the focus of the left optic, it can be in focus all over at close to middle distance but slightly out of focus at the bottom left corner at far distance. Is this an acceptable aberration or should I send them back? I also wear vari focals and have to position the eye pieces precisely to get optimum viewing, could this be the problem? They are new and otherwise the image is awesome.

Steve,

I'm not familiar with the Series 4 but that doesn't sound right.

Can I suggest you try a couple of things to try first. Without your glasses if possible, check one barrel at a time for the focal aberration pattern you mention. If there is a difference it needs to go back. Making sure you use the top half of your spectacles to avoid the transition zone, then do the test again.

This time using both eyes, turn the binocular round so you are looking through the objectives, find a nice horizontal line, like the edge of a window frame or the top of a fence and check if that line appears continuous across both views. (It's a bit easier to see with the barrels pushed together. If it doesn't it needs to go back.)

Hopefully it's just a question of getting the inter pupillary distance, eye relief and dioptre settings right, but binoculars do get knocked out of alignment etc. relatively frequently and if it doesn't look right it's more than likely it isn't.

David

I think it may be the bi focal, diopter, inter pupillary distance problem, I have fourteen days to solve this problem so thanks for your advice.

All bets are off with varifocals.
A single-correction pair for distance is the best.
Actually, single-correction contacts are better.