Of late, birdwatching or birding has become a popular hobby among people of various age groups. While your knowledge on the behavior of birds is a basic requirement when it comes to birdwatching, you also need to arm yourself with a good pair of binoculars if you are to increase your chances of spotting and more importantly, studying birds. Of the 10,000 odd species of birds found in the world, 914 are found in North America.
With so many options available, it's difficult to point out to one particular model and say, "this is the best". While animals can be easily spotted in the wild―relatively that is, spotting birds, which are smaller, quick, and boast of exceptional camouflage skills, is a tough task. This is where a good pair of binoculars comes into the picture. Binoculars for birdwatching, or birding binoculars as they are often referred to as, need to have certain features, like decent magnification, large objective lens, focus, etc.
Higher magnification no doubt gives a closer view of the target, but then, it also narrows the field of view, which is not ideal when it comes to birdwatching. It also affects the brightness and makes the device heavy, thus difficult to carry around. It's unlikely that you will want to carry something heavy on your birdwatching outing. Also, unless you are using a tripod or resorting to electronically powered stabilization, you will find it difficult to hold the binoculars with a high magnification steady. Hence, binoculars with magnification of 7× or 8× are popular among birdwatching enthusiasts.
The objective lens is the place from where light enters the binoculars. Bigger the lens, more light will enter, and that will make the view brighter, colors vibrant, and details finer. The only drawback of having a bigger objective lens is that it adds to the weight. A pair of binoculars with 50 mm lens can give you a perfect view, but it becomes difficult to carry it when you are in the woods. Thus, the most popular choice for birdwatching are 8× binoculars equipped with 40 mm objective lens.
Focusing is an important attribute in birdwatching, especially when the bird is at a distance of 15 feet or less. It helps you to get a sharp, detailed image of bird. The term 'close focus' refers to the shortest distance at which an object can be focused on by a pair of binoculars. The minimum close focal length increases with higher magnification. The binoculars with low close focus are considered the best for birdwatching. As birds keep moving, it is important that you are quick with the focusing aspect. Ideally, the binoculars should have a central focus, which can be turned smoothly by the index finger without having to put in much efforts.
The capacity of the binoculars largely depends on its prism design. There are two types of prism systems: the porro system and roof system. Binoculars with the porro prism have a z-shaped optical path, wherein the objective lenses are offset from the eyepieces. The user gets a wider field of view as the two offset prisms are mounted separately. A major drawback of porro prism system is its weak design, which makes the binoculars vulnerable to alignment issues if dropped.
In roof prism binoculars, objective lenses are in line with the eye pieces, while the prisms overlap each other. This gives the binoculars a slim shape, thus making it easier to carry it around. As the two separate prisms are bonded together, this design is considered stronger and durable. However, roof prism binoculars are costlier than their porro prism counterparts, as they have an expensive technology in place.
Besides these aspects, one should also take into consideration eye relief, i.e., the distance between your eye and the eye pieces, and the field of view, i.e., the widest dimension you get to see from a specific distance. Eye relief especially comes into the picture if you wear glasses, with the rule of the thumb being longer the better. While eye relief is measured in millimeter (mm), field of view is measured in feet per thousand yards.