It is not uncommon for optics buyers to be both confused and daunted by a list of binocular specifications. You may think, “Don’t you just pick them up and look through them?” Well, yes, you do just exactly that whenever possible — after you have set them up for yourself by making up to three different adjustments (more on that below). For birdwatchers, it is important to gain a basic understanding of how to operate birding binoculars, because, while most binoculars work for most people, some might not work for you. For years, I used binoculars that made birding a struggle, and when I see novice birders having a hard time in the field, I feel their pain and want to help!
It is easy to feel overwhelmed, especially when the opportunity to test-drive the optics in person is limited due to the pandemic. There are literally hundreds of models on the market and dozens of optics name brands. Many are clones of essentially the same product with a little different exterior. But many other well-known names have unique features.
And then there are all those technical-sounding specifications. What the heck are eye relief, interpupillary distance, field of view, and twist-out eyecups versus fold-down? Do I want 8x, 10x, 12x? Should I buy a 32mm, 42mm, or 50mm? I wear eyeglasses, so should I look for certain features? Hey, I found a binocular online for $20, will it work for birding? (The answer is decidedly, “No.”) How do I see the differences between $300, $1,000, and $3,000 binoculars? Should I get a spotting scope? Optics dealers such as the Cape May Bird Observatory are ready to handle all these features and questions. As you might expect, there are real differences in those price ranges, just as you’d find for bicycles, cars, golf clubs, and everything else.
The binocular that is best for you depends on how you intend to use it. If you want a pair for casual use, a compact often suffices. Hunters often use large objective lenses, such as 50mm or 56mm for dawn and dusk performance. An astronomer will want even larger objectives to gather boatloads of light; often they need higher magnification, too. As you might expect, you will definitely want to tripod-mount a 15×70 binocular, which are used for stargazing. Birders want something that lets them follow fast-moving, small birds, often early in the morning or at dusk.
Those three adjustments I mentioned earlier? First, twist the eyecups up if you don’t wear eyeglasses or down if you do wear them; this eliminates vignetting and lets you see the full field of view. Second, move the hinge of the binocular to adjust the interpupillary distance (the distance between the centers of your pupils), so you see one circular image. And third, to get a sharp image in both eyes, look at an object through the left eyepiece and adjust the focus wheel until it is sharp. Then look at the same object through the right eyepiece and adjust the diopter ring, which is next to the eyecup, until the image is sharp. Then, you’ll be good to go.
There’s a lot to consider with binoculars, but the good news is, we live in a golden age of optics, and there are many models available that will suit you just fine. In the July/August issue of BirdWatching, look for a deep, and hopefully entertaining, review of how to choose optics, and a roundup of what is available at different price points. We cannot cover every model, but you will know what to look for. We will focus primarily on binoculars, and we will also review spotting scopes.
Learn more about optics at CMBO’s online store www.FeatherEdgeOptics.orgOriginally Published