The basic equipment for every birder is a good pair of binoculars and a fieldguide for birds. You may wish to supplement your book with one of the many smartphone apps that are available. Apps are handy in the field but usually don’t have nearly as much information as you’ll find in a good fieldguide. Fieldguides have become very popular and the selection is really diverse. You’ll want to research different guides online and in person and ask other birders their opinions. In the end you’ll certainly buy several. Other equipment ranges from spotting scopes and tripods to specialize clothing. We’ll cover just binoculars here.
Take care when purchasing a pair of binoculars. There’s a wealth of information on the web as well as numerous merchants choose from. Before you buy a pair, we suggest you consider these guidelines:
Power, or magnification, should be between 7x and 10x, typically. Binoculars are specified as 7×35, for example, where the first number is magnification and the second is the diameter of the objective lens in millimeters (the larger lens at the front of the binocular). Magnification between 7 and 10 are sized well for most birding because as magnification increases the view shrinks, making it difficult to locate a bird, particularly one in the trees overhead. And holding the binocular steady enough to observe a bird will be noticeably more difficult at 10x than 7x. But if you’re strong, steady and really want to get good view, try 8.5x or 10x.
The binocular lens diameter is important for collecting light to see birds clearly. Don’t be tricked into buying the largest lens for a given power. The larger the lens the heavier the binoculars will weigh and tiring to hold. And under usual daylight conditions you don’t need to gather so much light – it’ll be “wasted” because your eye’s iris is smaller than at night and the extra light won’t enter.
Field of view (FOV) is the angular diameter you can see with the binoculars, often expressed as xx feet at yy feet distance. A wider FOV is important so you’ll more quickly locate a bird. The optical design determines the FOV but make sure you look carefully at the edges – if it’s too blurry consider another pair with better optical quality.
Eye relief, or pupil distance, is particularly important for eyeglass wearers. We don’t have to get technical but it’s important that you can see the full FOV hard edge even with your glasses on (assuming you’ll be wearing them in the field). If you see a smallish circle with fuzzy edges it may mean there’s insufficient eye relief.
Coatings and optical quality are getting very good these days so this isn’t the problem that it once was. Still, it’s worth checking carefully to make sure there are no “rainbow” colors when looking at, for example, a light pole silhouetted against a clear sky – blue on one side, red-orange on the other. Coatings, as well as the optical design can help alleviate glare and internal reflections. Again, look at high-contrast, light and dark objects to see if they’re sharp and clear without “ghosts” or other flares.
Alignment of the two barrels is critical. If they’re out of alignment you’ll be frustrated with two overlapping views or eye fatigue. How do you ascertain alignment? First focus the bins on a distant, distinct object such as a streetlamp. Slowly move the bins away from your face, trying to keep them pointed at the object. The two views should more or less continue to point at the object. If they drift apart, especially vertically, the alignment isn’t good. This is a qualitative measure since your eyes and brain can compensate to some extent. But if your eyes tire, try this test. And compare bins if you get a chance to try several at the same time – you’ll see a difference.
Weight was already mentioned as important for fatigue especially looking up into the trees. Some binocular styles tend to be lighter than others but other factors such as material or armor coating also influence weight. Higher magnification and larger objective lens binoculars tend to weigh more.
Other features: There are other design features to consider but the list above covers the most important ones. You’ll likely need to spend at least several hundred dollars to get a decent pair of binoculars. Prices can easily surpass $2000 for some of the highest quality pairs. You’ll want to sample several regardless of your price point. This is a good reason to join a field trip; birders will be generally be happy to tell you about the pros and cons of their choice pair and most likely let you try theirs.