There are warning signs that you need new binoculars. Maybe your current pair was handed down from your grandfather who used them in the war. Perhaps you’ve changed but your binoculars haven’t. Or — and here’s a big one — you can’t see much through them and, besides, they give you a headache.
This third sign is a classic. Many old binoculars are out of alignment and the owner doesn’t even know it. Binoculars use lenses and prisms to deliver twin images to your eyes. These images must arrive together, straight and true. But age and hard use can knock interior elements off kilter. One image arrives slightly askew. Your brain tries to correct the flaw, so it may not be instantly obvious, but eyestrain and headache are frequent results. If you find yourself closing one eye while using your binoculars, I’ll wager this is the problem.
Here is a simple test. Put the binoculars up to your eyes and focus on a horizontally straight object in the distance, such as a shoreline or rooftop. The line will look straight. Slowly move the binoculars away from your eyes while still looking through them. If the line in one eyepiece is above the other, the binoculars are out of alignment. Old ones and cheap ones aren’t worth repairing, but higher-quality binoculars can and should be fixed. Often the manufacturer will do it cheaply, or even for free, since reputation is vital to a company’s brand.
Some binoculars have lens quality problems. Ideally, you should see a sharp image throughout. Poor lenses are blurry on the edges. Read a distant sign and look for letters that are clear in the center and fuzzy at the sides.
Perhaps your needs have changed but your binoculars haven’t. You’re a better birder now. High-quality binoculars won’t help a novice birder identify that female Canada warbler peeking out of the understory, but now that your skills have improved, grabbing a visual piece of the bird in dim light may be all you need for identification. Better optics give you an edge, especially at dawn and dusk.
Maybe your eyes have changed. Some binoculars are easier to use with glasses than others. Binoculars are designed to deliver the image at a precise point behind the eyepiece. The eyecups should adjust such that your eyeballs meet the image at that point. This is called eye relief. At the proper eye relief, you should see one image that fills your view without much darkness surrounding it. Wearing eyeglasses can change the point at which your eyes meet the image. It’s human nature to get used to an improper view. Have you been living with that awhile?
I did. My old binoculars did not adjust well to my increasing need to wear eyeglasses. I quickly acquired the habit of whipping my glasses off whenever I used my binoculars. I now own binoculars that properly adjust to my glasses, but I can’t break the habit. Some day on a boat trip, I will whip my glasses off and fumble them into the sea.
It’s also time to upgrade when your activities change. Compact 8×20 binoculars might have packed well when you were canoeing and mountaineering, but the more you use them for birding, the less you’ll like them. Too dim. The old 10x50s might be fine sitting on the windowsill next to the bird feeder, but they weigh like a brick around your neck on a long day in the field.
And, ahem, perhaps the purchase of your current binoculars wasn’t the wisest. Some folks get excited about binoculars with special features. At the risk of offending manufacturers, I loathe binoculars that zoom. They are heavy, the image is darker than necessary, and the image under higher magnification tends to be blurry and unsteady. Some binoculars have image stabilization. These can be great on the ocean, but how often are you on the ocean? Is the extra weight and bulk worth the few times you actually take advantage of the feature? A few models come with built-in cameras. This hybrid quickly leads to disappointment. Generally, both the optics and the camera are pretty cheesy. Some may produce acceptable results. But if you are serious about photographic magnification, you’ll soon invest in a superior camera and leave the all-in-one binoculars in the cellar.
If you recognize any of these flaws in your own binoculars, perhaps somebody on eBay will take them off your hands. Let’s hope they haven’t read this column.
Bob Duchesne serves as a Maine Audubon trustee and vice president of its Penobscot Valley Chapter. Bob developed the Maine Birding Trail, with information at www.mainebirdingtrail.com. Bob can be reached at firstname.lastname@example.org.