One of the most important tools you'll need to get started birding is a good set of binoculars. Binoculars come in a variety of shapes, styles and magnifications, however in this article we'll help to dispel some of the common mistake and marketing ploys as well as hopefully provide rational unobjectionable advice to help to get started birding.
The first thing to notice with any set of binoculars is the difference between Porro prism and Roof prism binoculars. A prism corrects the inverted and reversed image you would see without them. The difference between Porro and Roof comes from how they “flip the image”.
Porro prism models will deliver good optics for the dollar, but lack the durability and compact styling of roof prism models. In addition, many Porros are not waterproof. Roof prism binoculars generally weigh less than similar Porro types and are often water-resistant or water-proof.
Roof prism binoculars (on the right, below), are slim, lightweight and are often waterproof. Porro prisms (on the left) provide increased image depth because their off-set design, but are often heavier and are more suited for people with larger hands.
Take Away: Either design will not dramatically alter the image of the bird you see. Porro vs Roof comes down to convenience and styling.
When researching binoculars you might have noticed that every binocular or spotting scope name is followed by a series of two numbers separated by an “x”. These numbers refer to the magnification (the first number) and the aperture (the second number) We'll get to the aperture later. Most birders use binoculars with a magnification of either 8x or 10x. Spotting scope often range from 40x-80x.
The reason, although some model binoculars do go higher than that, that most birders don't use more than 10x is due to the fact that as you increase the magnification you exponentially increase the vibration from hand shake. While you may be able to see a larger bird you'll have much more trouble holding your hands steady enough to make out the distinct field marks. For photographers reference an 8x set of binoculars is close to the same view as a 400mm lens (assuming a standard 35mm camera and 50mm lens as a standard human eye.)
Aperture or brightness is the second number in the name of the binoculars or spotting scope. This refers to the amount of light that the binoculars let in. Really its a mm measurement of the size of the lens itself. Camera lens use the same system. General rule of thumb: the larger the number the more light, brightness and clarity your image will be. 8X42 is the most common binocular setup.
This section could get really scientific but seeing how this is a beginners guide let's leave it at this. One of the most important determiners of good optics and light transmission is determined by the type of glass and the number of coatings. The best and most expensive binoculars contain BaK-4 glass and are fully multicoated to reduce stray light and to increase contrast. BaK-7 glass is your next choice and is usually found in binoculars setups under $100.
Everything visible within the dark periphery seen when you look through a binocular is consider the field of view. A larger field of view is beneficial when scanning trees or a lake. You'll be able to see more of the object at your binoculars magnification.
Eye relief is the distance, measured in millimeters, your eyes can be from the eyepieces and still see the entire field of view. Higher-power binoculars generally have shorter eye relief, as do those employing Porro prisms. This is an important number especially for those who wear glasses. A larger number will ensure you can wear your glasses and still see the full field of view.
Before you buy any optics it's a good idea to talk to other birders, research online, and even try different models in store. Find a pair with good optics that are easy to focus and fit well in your hand. Take weight into consideration as well. Put then around your neck and let them dangle. Make sure you can handle the weight for a couple hours. Lastly, get a good neck strap...you'll thank me later.