We're going to talk a little bit about digital camera lenses or just camera lenses in general. Now, any DSLR camera, which stand for Digital Single Lens Reflex with the word lens in there, has a lens that affixes to the front of the camera. Something kind of like this. This happens to be a wide angle lens. There are many, many, many different kinds of lenses. This one in particular zooms from the focal length of 17 millimeters, which is quite wide, into a focal length of 35 millimeters.
Now there's other lenses out there. This would be great for shooting something like rock and roll. This, on the other hand, is a 70 to 200 millimeter lens. This is better for stuff like fast action sports, football.
Now, not all lenses zoom like the two I just showed you. This one over here is just a fixed focal 85 millimeter lens. Really good for portrait photography. So this vast number of lenses gives you a lot of options in terms of what you're shooting to get the kind of look that you want. It's just going to be a nice tight crop with no distortion. Whereas this wide angle lens is going to have a lot of distortion, but you get a lot in the frame.
So like I said, all digital SLR cameras need a lens to take pictures otherwise you just have a mirror and a sensor in there. Simply take your lens, remove the caps, and attach it on. And that's one of the nice things about digital photography if you have an SLR, is you can switch your lenses out. Whereas, if you're using a point-and-shoot camera, the lens is fixed and you obviously can't remove it.
So when you take a picture, what the lens physically does is there's multiple elements inside of this and those elements bring the light in, obviously into focus, and direct it back into the sensor that's behind the mirror. That's how you get your image. The better the lens quality, the better the image is going to look. Finer lenses, more expensive lenses have just better ground glass with better coatings that help get rid of lens flair, chromatic aberration.
And that's just a couple of basics about lenses for digital SLRs.