People who love watching birds tend to spend numerous hours trekking over the land to get a glimpse and the binoculars they use should not hinder them in any way. If you are looking for binoculars to aid you in bird watching then you need to ensure that the binoculars are able to endure and hold up to any weather conditions. One of the must have in a bird watching binocular is that they should be easy and fast to focus and useful even when light is dim. All binoculars have three parts which are the objective lens that gets the upside image, the prism that turns the image on the right side and the eyepiece that makes the image larger.
The first thing you must know is that the binocular identification normally comes in a format of two numbers for example 7x35. The first number refers to its magnification power while the second one refers to its objective lens diameter. The first number which is magnification number simply tells you how many times closer the image is going to appear when you use the binoculars while on the other hand, the objective diameter tells you how much light it will allow in millimeters. This means that the larger the diameter, the greater the amount of light that will be gathered and in effect the user gets a brighter view of the object.
You can also use the numbers in the binocular identification as a way of determining its specifications; they are also identified using their exit pupil as well as their relative brightness. The exit pupil can be referred to as that brightness of a target image when it is in a low light setting. This is normally compared with how wide your pupil usually widens in that amount of light; it is calculated using by dividing the lens' objective diameter by the magnification power. The relative brightness, on the other hand becomes the square of the exit pupil. This is a specification that refers to how brightly the object will appear to our eyes. A higher relative brightness means you will have a clearer and brighter image.
The next important specification you need to look for is known as eye relief; this is simply the distance between the binocular eye pieces and the eyes that will allow you to see the entire view of the surrounding. The convenience that this brings is that you can comfortably hold the binoculars from some distance away from your eyes; this is especially important for those people who wear eyeglasses. The greater the eye relief the more convenient it is.