Just like jeans and tube tops, it's pretty obvious when you take a good look at binoculars that one size doesn't necessarily fit all. Different activities will require you to look for some variables in your binoculars, which could have a big effect on your optical success.
Hunting is great example of how buying bigger binoculars is not always better. Consider what you'll be using them for: You'll need a hand-held pair, for instance, that's easy to manipulate and store. Anything above a 10x magnification will probably require a mount, and a spotting scope (a smaller telescope designed for daytime viewing) is going to be more useful if you're looking at something so far out. So while you can spend up to $1,700 on hunting binoculars, you might want to consider a brand like Bushnell or Tasco that has perfectly adequate $70 pairs.
If you're fishing, especially in marine waters, you might be surprised to know that binoculars can be helpful. In fact, many binoculars are really useful for spotting fish or other marine life. When looking for fishing binoculars, remember that ridiculously large magnification is going to be unhelpful. More magnification means that your field of view decreases, which isn't very helpful somewhere as large as, say, an ocean. A large field of view also makes motion more obvious, and thus waves or light reflections can get in the way of spotting something. Sure, there's the 18x magnification binocs for $2,000, but you're probably better spending $100 on the 7x Barska brand -- or even Barska's $40 steal. Just might want to remember to buy those suckers waterproof.
Now, birding without binoculars is like painting with only your eyes. From teeny hummingbirds to eagles and ospreys, being able to see the birds really makes birding a lot more fun. Bird-watching binoculars are much like hunting binoculars, in the sense that an extremely high magnification is not going to help you spot a tiny bird in a big forest. A magnification between 7x and 10x is generally recommended, although with a 7x, you're going to be able see a brighter image and -- in a flock of birds -- more individuals. Choose an aperture between 30 and 50 to get the greatest light capture and spot the prettiest colors on your black-throated green warbler. Anything bigger, and you'll have to rest your arms on something to keep the binoculars steady.
It's absolutely possible to get quality birding binoculars for under $150. Nikon and Alpen both offer affordable prices for decent buys. If you're really interested in spending big bucks, Zeiss and Swarovski have extremely high-quality brands that can go for as much as $3,000.
Still haven't satisfied your need to learn more about binoculars? Take a good look at the next page to get some binocular background and some supercool binoculars for spies working under the cover of darkness.