An easy how-to-guide to understanding, selecting, and using the right optics essential to bird watching.
First, let’s cover some bird watching optics basics. Consider the purpose of a pair of binoculars – to bring your subject closer to you as clearly as possible. Optics do this basically through a series of lenses stacked inside a tube, and the nature of these elements are what determine the performance and price of binoculars or a spotting scope.
Magnification
Notice that all optics have 2 numbers in their description, such as 8×42. The first number, 8, is the magnification, and is the number of times the subject is enlarged through the binoculars. So an 8x or 8 power makes things appear 8 times larger and brings you 8 times closer to the subject. While you would think the more magnification, the better, it comes at a cost – both a financial cost, and a usefulness cost. Greater magnification is more expensive, plus it can make it difficult to track the subject if you are too close. Too much magnification can make things shaky, requiring a tripod for stabilization. For birding binoculars, 7x to 10x is best, with 8x being most popular. Magnification above 10x is best used with a spotting scope and tripod.
Lens Diameter
The second number in the 8×42 description, the 42, is the objective lens diameter, or how wide, in millimeters, the lens is. The objective lens is the (often wider) part away from your eyes, not the part next to your eyes. Wider lenses let in more light, making the subject clearer and brighter. Again, you would think the larger the diameter, the better, and again there are associated costs. Larger diameter optics cost more and are heavier. So like magnification, you want to get enough diameter, but no more, than needed for your particular purpose. For birding, 30mm to 42mm is a good balance between performance and size.
Other Features
There are a host of other, often more subjective, features that impact your perfect scope or pair of binoculars. But we don’t want to get too deep in the weeds. Simply testing out potential optics and comparing with the following in mind will help, without overwhelming you:
- Ease of Focus relies on one central focusing knob that is positioned comfortably under the index finger so that you can easily, smoothly, and quickly get your subject in clear view before it flies off.
- Weight and Feel is subjective and why you should try out binoculars in person. Determine if they fit well in your hands and are comfortable enough to use for extended periods. (Stop by Chirp to test some out!)
- Field of View, or the visible area seen through your binoculars, can vary widely even among optics with the same specifications. Field of view is not related to the lens diameter. A small field of view can make it difficult to track your subject.
- Close Focus is the measure of how close you can get to your subject and still be clearly in focus. Under 6.5 feet is good.
- Eye relief is the distance that an eyepiece can be held away from the eye and still see the whole Field of View. Eye relief is accomplished through adjustable eye cups, and is achieved when there is no vignetting, shadowing, or obstruction when looking through the binocular lenses. If you wear glasses, eye relief is essential, and eliminates the need to remove glasses when using optics.
- Roof Prism Design allows light to go straight through the barrels to your eyes, making them more compact, streamlined, and smaller than older designs. Porro prisms, while simpler and cheaper to manufacturer, zig-zag light through the binocular to get to your eye and are generally outdated.
- Water Proofing protects your investment from bad weather and unintended slips into water by preventing water entry. Note that weather proof does not mean the same thing and is inferior.
- Fog Proofing prevents lenses from fogging up in moist or humid conditions by filling the optics with dry nitrogen or argon gas. Sometimes referred to as “nitrogen purged” or “nitrogen filled.” Most mid- and higher-priced binoculars are both water and fog proof.
- Glass Types range from inexpensive “standard” to the preferred high-quality “Extra Low Dispersion (ED)” that helps reduce chromatic aberration (the inability of the lens to focus all the colors to a single point, which causes undesirable color fringing around the edges of the image).
- Lens Coatings prevent significant reflected lost light that makes an image dark. Simply “Coated” lenses may have only a single surface coated, are inexpensive, and perform poorly. “Fully Multi-Coated” lenses have all external and internal air-to-glass surfaces multi-coated, which costs the most to manufacture and lets the most amount of light through to your eye.
- Warranty protection is an indicator of manufacturer confidence in their optics. Comprehensive warranties are available with better brands, such as Nikon or Zeiss, and can even provide “no fault” protection.
Making a Good Binocular Buying Decision
Armed with an understanding of how birding optics work and how different features impact usability, you are now prepared to buy. Here are key considerations:
- Buy the best binoculars you can afford. You can spend from roughly $100 to $3000 on a pair of binoculars or a spotting scope. Unlike modern consumer electronics, good optics can last a lifetime and are not subject to rapid obsolescence. Over time, a significant optics investment can actually make good financial sense.
- Pick a magnification. Most birdwatchers use 8x or 10x, with 8×42 (pronounced “eight by forty-two”) being the most popular configuration for good reason.
- Test them out. Trying different pairs in person to see what feels best will help you make a confident buying decision.
- Watch for bright, crisp, accurate color. How do things look?
- Company matters. The brand you choose, and the dealer you purchase from should confidently support, not detract from, your bird watching experience. Choose a proven brand, with a good warranty, from a reputable authorized dealer with a physical location and real people who can guide you.
Summary
Simply stated, to buy the perfect pair of birding binoculars: test out a popular configuration (8×42 or 10×42), investing as much as you can, on a proven brand, from a reputable authorized dealer you can rely on. The result? Years of enhanced bird watching pleasure.
