The Lake County Astronomical Society

Misaligned Binoculars

Have you ever looked through a pair of binoculars and found that you're unable to merge the two separate images into a single well-focused image? Chances are that the two barrels or optics are misaligned. (Cheap binoculars often are a bit misaligned from day one.) High quality binoculars are designed to be very durable and are very well aligned both mechanically and optically. They usually can maintain that alignment even with rough handling. If you have an expensive pair that has become misaligned, you should return them to the manufacturer for service. If they are a cheap pair, you could take them apart and get two finder scopes out of the deal. (They're virtually worthless as binoculars.) While it's not a good idea to take binoculars apart, rather than scrapping them you could try the following process explained by telescope author Philip Harrington:

"Unscrew the end ring by one of the objectives. With it removed, you should see a retaining ring surrounding the lens itself. Using a jeweler's screwdriver, carefully unscrew that ring by sticking the screwdriver's blade into one of the two thin slots on the retaining ring itself. Applying pressure toward the outer edge of the housing, turn the screwdriver counterclockwise. Once the retaining ring is off, you should now see that there is a pair of spacers around the outer edge of the objective. These rings are slightly eccentric and serve as shims to align the objective with the internal prism (working like a cam). It is possible (though unlikely) that you can adjust these shims to realign the binoculars. Just be careful not to turn the binoculars downward when doing this, since the objective will fall out."