How to Focus Binoculars

In order to get the most out of your birding binoculars, it is important that you not only know how to focus but how to calibrate them correctly. Amazingly people quite often will just start using their new pair of binoculars right out of the box without calibrating them first. There are two adjustment elements on a good pair of birding binoculars, the Focus Adjustment and the Diopter Adjustment Ring. The Focus Adjustment allows you to focus on an object with both barrels at one time. The Diopter Adjustment Ring allows you to calibrate the binoculars for differences between your right eye and your left eye.

The first step is to calibrate your new birding binoculars. This only needs to be done once and only takes a few minutes. Quality binoculars will have a Diopter Adjustment Ring, typically on either the right or left barrel near the eyepiece. On your higher end binoculars the Diopter Adjustment Ring often is lockable to prevent the setting from being adjusted accidently.

1. If the Diopter Adjustment Ring is on the right barrel, start by covering the right barrel with a piece of paper (if the adjustment ring is on the left barrel, cover the left barrel).

2. Look through the binoculars keeping both eyes open (closing one eye can change the way your eye focuses). At this point you will only be viewing out of the left eye. Using the Focus Adjustment, adjust the binoculars until an object approximately 30 feet away becomes sharp.

3. Now move the paper from the front of the right barrel and cover the left barrel, which will leave you viewing only out of the right eye. Now looking at the same object, focus using the Diopter Adjustment Ring until once again the object becomes sharp.

4. Remove the paper and while looking through both barrels, the object should be clear and sharp. You now have your binoculars properly calibrated for your eyes.