A lot of people find buying binoculars confusing. When you try to make a purchase you are going to be confronted with numbers like 7x35 which you need to be clear on in order to get the right pair. There are also a lot of specialized features like compact binoculars or stabilized binoculars that you will have to consider. If you think about what you want to use the binoculars for everything will fall into place quite nicely, so this is something you will need to think about before you start looking.
Magnification and lens diameter are far and away the most important things that you are going to want to keep in mind when you are choosing binoculars. These are clearly labeled on all binoculars with a number like 7x35 or whatever. Magnification is determined by the first number and that is nothing more than how many times closer an object will seem. The diameter of the lens will be the number you see second and it is shown in millimeters. The field of view is going to be bigger if you use a bigger lens diameter.Unfortunately it's not just a matter of buying the binoculars that have biggest numbers, that would be much too straightforward. For example choosing a high magnification will make it difficult to pick up things that are moving, not really a good choice for something like bird watching. Having a big lens diameter will allow you an excellent field of view but it will also result in large and heavy binoculars, not something you want if you have to carry them a long way.
The brightness of a pair of binoculars is determined by the size of the exit pupil and this is another major thing that will need to be kept in mind. If you divide the lens diameter by the magnification you will find the size of the exit pupil. The larger the exit pupil is the more light will get to your eye. This can be a problem in bright sunshine but is almost a necessity if you use your binoculars when it is dark. For daytime use or general purpose binoculars an exit pupil size of 3 to 5 mm is a good choice but for use at night you are going to want at least 7 mm.
There are a few other factors that you are going to have to keep in mind but they are for the most part just down to what you feel comfortable with. Factors like how you focus the binoculars or what kind of prism is used can be important to some buyers while others aren't going to care. You are also going to want to keep in mind any of the specialized types of binoculars that are available like water proof binoculars or stabilized binoculars. Keeping how you want to use the binoculars in mind should help to make certain that you make the right choice for your needs.
