"Why wide?" one might ask. Hearing the words "wide angle lens" doesn't really mean anything to me, it took me awhile to find a way to understand what it really means, so I'll try to explain it the way I came to understand it.
Well, here’s why!
Basically, a “wide” lens is any lens rated at a focal length of 35mm or lower on a 35mm camera and 50mm or so and lower on a medium format camera. For this reason, wide angle lenses tend to be short and fat looking. “Still,” you might say," that doesn’t mean much to me." So, let’s break it down this way: a camera exposes film with light like you project a movie onto a screen. Light hits the lens outside of the camera, is “funneled” through the lens, then projected at the correct scale onto the film. The difference between a wide lens or a normal or telephoto lens is that a wide lens makes the scale of the light (the image) it is projecting onto the film smaller, thus allowing more of what can be seen fit onto the amount of the negative the camera allows to be exposed at one time. It’s somewhat like when you move a projector closer from a screen, since now the angle the light is traveling is greater at less of a distance, the scale of the things hitting the screen is smaller. The less distance the light travels, the greater the angle required to cover the same space.
“You still haven’t answered the question!” you’re probably thinking, and I promise I’ll address it now that we have that background. So, why a wide angle lens? To fit more in the same space. Anyone who has played with a zoom lens on a camera understands what it’s like to watch the focal length go from 35mm to 50mm to 75mm and vice-versa, the amount of what you can see gets less one way and greater the other. If you were using a fixed focal length lens, you would have to move yourself to have the same effect. So, one benefit of a wide angle lens is that you can be closer to something and still fit more into the frame, like if there was a wall or street behind you, but you wanted more of what is in front of you to fit into the frame and you can’t back up any. Another way to think about it is to imagine you’re standing on the side of a mountain, about to take a picture of a valley with a 35mm film camera. You could use your 50mm lens, and make the scale of things appear about 1:1 to what you’re seeing, or you could use your awesome 17mm lens (because you’re a millionaire and can buy any lens you want) and make everything look smaller. And, like I said, you’ll technically get more stuff in your shot on the same size 35mm frame. So, wide angle lenses allow closer proximity to a subject and the ability to make the scale of things appear smaller. See, I did have an answer, it just took me awhile to get there. Hopefully, now, you understand why you want it wide.