Larger Lens Means Larger, Heavier Binoculars

Many companies now offer their lines of binoculars in three categories, compact, mid-size, and full-size. When archery hunting a big pair of binoculars can get in the way during crucial moments while trying to get a shot. However, most compact series binoculars lack the light gathering capabilities that mid-size and full-size models have. There are hunters who like to use compact binoculars that can easily fit in a shirt pocket when not in use. Having a good set of compact binoculars can be a great asset when you don’t need to see more than 100 yards or so. However in open areas or in low light situations, they can hinder your ability to judge an animal at a distance. Choosing the right size range is the next step in narrowing down which pair is right for you.
What objective power is needed? This is probably the most commonly asked question in determining which pair of binoculars to choose. Magnification averages from 7X to 16X for most manufactures, with larger magnification models available.  Some hunters who primarily hunt dense brush or thickets don’t need that much magnification, while other hunters out west need magnifications greater than that while glassing distant ridges for big game. Most archery hunters don’t need more than 7X or 8X binoculars, but if you are also a rifle hunter that extra little bit of power can be a tremendous help. Magnification is also dependent on the size of your objective lens for how well they will perform during those early mornings, late evenings, or cloudy days.
The final piece of the puzzle is the quality of the lenses and prisms in your binoculars. The old saying “you get what you pay for” applies here to an extent. Most of the binoculars in the $200+ price range feature better lenses, lens coatings, and prisms.  Good quality lenses will be smooth and symmetrical in size through out. Even small flaws, waves, or discrepancies in lens density can mean poorer clarity and viewing performance. The best way to see this difference is to pick up a $25 pair of compact binoculars, and compare them to a larger $300 pair. You should immediately see a huge difference in brightness and clarity through the entire field of view. Some less expensive binoculars are very clear in the center of the viewing frame, but get blurry as you look towards the edges of the field of view. The coatings that manufacturers put on lenses also help clarity and light gathering capabilities. 
The power is listed by a pair of number such as 10×25, pronounced “ten-by-twenty five”. The first number is the amount of magnification. In this case the image would be magnified by a power of 10, or in other words would appear 10 times closer than without the binoculars. The second number listed is the size of the lens in millimeters. In this case the lens is 25 mm in diameter. So the larger the first number, the closer your subject will appear to be. The lens size determines how much light enters the binoculars. The more light, the sharper and brighter the image will be. So at first glance it would seem you would want binoculars with the highest power measurements as possible. But you must consider that larger lenses mean larger and heavier binoculars, and in most cases, more expensive too. So it is best to first consider what you plan to use your new binoculars for.
Once you have decided where you will be using your binoculars and what you will mainly be using your binoculars to observe, you can then make a smart decision about the size and power you need. And with most purchases, you should first know your budget and then match your needs to your budget.