Optical aids make for better birding. Practically everyone who develops a serious interest in birds will pick up binoculars pretty quickly. For backyard birding or for pursuing warblers in the woods, binoculars may be all you need. But for some kinds of observation—scanning the waterfowl far out on a lake, studying shorebirds on a wide-open mudflat, or checking out that hawk perched on a distant snag—even the best binoculars won’t do the trick.
That’s when a spotting scope can make all the difference in being able to identify and enjoy more birds. Beyond merely being able to pin IDs on distant birds, regular use of a scope will allow you to learn details you would never notice otherwise.
For details on specific models, check out the top picks in our complete Audubon Guide to Scopes.
Binoculars are usually described first by their magnification, such as “7X” or “7 power.” That’s not the case with spotting scopes, because their magnification is usually determined by the choice of eyepieces that you use. Instead, the big number that’s used is the diameter of the objective (front) lens, in millimeters. Many of the most popular birding scopes have objective lenses of 50 to 80 mm. Bigger lenses let in more light, but they also add to the bulk and weight of the scope.
Eyepieces: Fixed vs. Zoom
Some scopes come with the eyepiece permanently attached, while others have detachable eyepieces and multiple choices available. If you’re buying a fixed, or single-power eyepiece, don’t assume that the higher magnifications are better. For most birding situations, an eyepiece of between 20X and 30X will be most effective. Heat shimmer and vibrations frequently obscure the view at higher magnifications.
Zoom eyepieces are often the best for birding. Some popular zooms are 20-40X, 20-60X, or 25- 50X. You can use the lowest power while you locate the bird and center it, and then zoom in (as far as the heat shimmer will allow) to get a closer study.
The quality of the glass used in a scope makes a huge difference in the quality of the image delivered to your eye. Check the specifications provided by the manufacturer to make sure you are getting good lenses for the price.
Ordinary glass blocks a certain amount of the light passing through it. Modern lens coatings improve the transmission of light, letting more of it through and giving you a brighter image. All good scopes now use coated lenses, and multi-coated lenses are the top standard.
Low-quality lenses produce chromatic aberrations. This “fringing” of colors around an object is produced by lens dispersion, with colors of different wavelengths passing through the glass unequally and focusing on slightly different points. Good optics avoid this by using ED glass, which stands for “Extra-low Dispersion.” With all colors focusing on the same point, the image is noticeably sharper. Unfortunately, not all optics makers use the same terminology, and some may designate their low-dispersion lenses as HD, XD, or APO. Check to see what term is used by each brand, or talk to your optics dealer about the characteristics of the lenses used.
Good quality lenses add to the cost of a scope, of course, but they’re well worth the investment. If you have to choose between higher quality lenses and higher power, the sharpest and clearest image will always make for a more satisfying experience.
Straight vs Angled
Most good scope models come in two configurations: straight and angled. If you generally go birding alone and if you get a sturdy, tall tripod, the straight-through view may be a better choice. You can set the tripod so the scope is at your eye level, and use it for long periods of scanning.
However, if you’re likely to be birding with others, sharing is easier with an angled scope, with which you look down at about a 45-degree angle into the eyepiece. You can set the height so that the shortest person in your group can reach it, and then taller people simply have to lean over a little farther. An angled eyepiece also works better when you’re aiming up at birds overhead. And if you use a scope for sketching birds in the field, as I often do, an angled eyepiece is easier to use: You can look back and forth from the scope to your sketchbook with only a slight movement.
Focusing and Close Focusing
Typically you focus by turning a ring or knob on the barrel of the scope, which moves internal elements to give you a sharp picture. Some models have two-step focusing, with one knob that quickly shifts from close-up to infinity and one that makes much smaller adjustments for fine-tuned focus. Some birders like this approach and some don’t, so it’s a matter of personal preference. If you have a chance to try out a scope, check to see if the focusing mechanism feels comfortable for you.
Odd as it might seem, a spotting scope’s capacity for focusing on close-up objects is important. Birders aren’t always straining to identify distant specks; sometimes we’re trying to see fine details on a bird that isn’t far away. For example, we might be looking for critical marks on a hummingbird visiting a feeder, studying it from just a few yards away.
Many manufacturers now list the minimum focusing distance among the other specifications for scope models, but if you get a chance, it’s still a good idea to test it for yourself. Ideally any scope for birding should be able to focus down to 20 feet or closer.
Cases and Lens Caps
Some manufacturers provide heavy canvas covers in which to store the scope when it’s not in use. Some of these covers are designed so that they can be left on the scope even while it’s in use, with just the ends opening up. These can be helpful in protecting the scope against blowing dust or random accidents.
Almost all telescopes come with some kind of lens caps, and the better ones are solid and attach firmly. The trick is to avoid losing them while you’re out birding. Some of my friends have specific systems they use, such as always putting the lens caps in a secure pocket while birding, and putting them back on the scope as soon as a birding session is over.
Don’t Skimp on Support
When you’re figuring out your scope-buying budget, don’t forget to factor in the cost of a tripod. A tripod for a birding scope doesn’t have to be quite as rock-solid as one for photography, but you’ll want one firm enough to give you a steady view, even in windy conditions. Check to make sure the tripod will extend far enough to put the scope at a height that’s comfortable for long sessions.
Try Before You Buy
No matter how much you research the specifications for different models, there’s no substitute for actually trying out a scope for yourself. Some of the bigger nature centers or wild bird stores may have several different models on hand, giving you a chance to compare. You’re likely to find an even bigger selection at major birding festivals, where many optics companies will have representatives on hand with a full line of products. It’s a great opportunity to try a range of models and find your personal favorites. Don’t be shy about taking your time and asking to compare different models. A good spotting scope is a major investment that can add to your enjoyment of birding for many years.