Binoculars Redux

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I’m not going to provide another review of binoculars as there are lots of those on the WWW. Frankly, I think the best thing is to try binoculars in person and if they work for you, that’s what you want. You can get a cheap pair that work well, although the more expensive ones tend to have higher quality optics.

On every field trip I lead look at the variety of binoculars the group brings. I have seen birdwatchers carrying sizes from 8 x 20 to 10 x 50. As you may know, the first number is the magnification and the second number the width of the objective lens – the one in the front. Obviously, a higher magnification is good, and so is the width of the lens as that gives you a wider field of view and lets in more light. The way binoculars are built, though, the larger the numbers are the heavier the binoculars. So a 10 x 50 pair is good for searching for submarines from the deck of a battleship but too unwieldy for birdwatching.

Well, what about an 8 x 20? Nice and lightweight with good magnification. Now the problem is that the binoculars have a narrow field of view and let in a minimal amount of light. Good for watching birds that don’t move much and are in a bright light. Otherwise these eyepieces are really best for ballgames and operas.

First thing I do is tell the field trip attendees that their two eyes are different strengths, like arms and legs. So to adjust the binoculars to compensate, shut your right eye and look at a distant object. Now use the central focus knob to focus. Then shut your left eye and as your right eye looks at the same object, turn the diopter ring (right eye focusing wheel) at the base of the right eyepiece to focus. Now your binoculars are adjusted for both eyes. There are rubber eyecups on the eyepieces that are designed to be fully extended, but if you wear glasses, you’ll have to see what extension length works best. For a wider view, retract the eyecups.

Then I tell people how to use binoculars. You wouldn’t think that necessary, but I’m always surprised. (A little off the subject but when I was on a Kenya safari, I showed binoculars to some native Maasai children. They looked through them backwards and tried to look at the sun.) Haven’t had that experience at home, yet. The main thing I point out is that binoculars are for detail, not finding birds. Your eyes have a much wider field of view, so spot the bird with your eyes and then zoom in on it with your binoculars.

From personal experience, I have learned that it is not a good idea to place your binoculars on top of a car or boat. And if you drop your binoculars, or after clumsy handling, the two mini-telescopes that make up the binoculars may get out of collimation, that is, not properly aligned. So if you are unable to obtain good focus, you may need a technician to adjust the lenses.

With increasing birding experience, just like with cars, stereos, and musical instruments, you’ll eventually want to move up to a better grade of binoculars. When you do, you may wish to donate your old binoculars to a worthy cause. But with a bit of care, almost any pair of binocs can last a lifetime, not counting boat or car incidents.

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