ABSTRACT
With a zoom lens you can change focal length by turning a ring on the lens, which is called a twist zoom. On some older lenses you would zoom by pushing and pulling the lens forward and back (a push/pull zoom). Zoom lenses give you a lot of flexibility because you can adjust your composition by turning the zoom ring. You may not have to move closer or further from your subject if you can get the shot you want by zooming in (a closer view) or zooming out (a wider view). The zoom lenses made today are very good quality and can produce excellent photos. They can be a compact way to travel because you get many focal lengths in a single lens. Think of it this way: with a 17-55 mm lens you have a 17 mm lens, a 24 mm lens, a 35 mm lens, and a 50 mm lens all combined into one lens. There are a variety of zoom lenses available. Autofocus zoom lenses have two rings on the outside that rotate. One is the zoom ring and the other is the focusing ring. The zoom ring is usually larger and often toward the back of the lens, with the focusing ring closer to the front. In some lenses the focusing ring is actually the front of the lens.
