Most consumers usually think of a zoom lens simply as the type of lens that allows distant objects to appear closer than they really are. Although this is true, there are a number of other things that zoom lenses allow photographers to do. Understanding their mechanics is imperative in order to choose the right Nikon zoom lens for your digital SLR.

As opposed to a prime lens that has a fixed focal length, zoom lenses are an assembly of lenses that allows the focal length to change between two points (and anywhere in between). At its most basic, the focal length of a lens determines how much of a wide or telephoto lens it is. 50mm is considered 'normal' (it sees what the eye sees), while anything below is a wide lens and anything above is a telephoto.

Nikon zoom lenses come in a variety of sizes. Some cover a wide spectrum of focal lengths, such as a the Nikkor 28-200mm. Others focus primarily on the telephoto end, such as a 70-200mm. The longer the focal length, the narrower the depth of field. This means that only a small range can be in sharp focus. On the other end, wide lenses have a tendency of keeping the entire picture in focus, while slightly warping it at the same time to include more information.

In the realm of digital, the power of a zoom lens is often confused. Many cameras now have the ability to zoom farther, thanks to 'digital zooming.' This is an artificial enhancement of the image, which reduces the resolution of an image to magnify it. Using a quality Nikon zoom lens is a more effective way to create quality images without resorting to digital tricks.