Fixed Focal Length
Fixed lenses offer some advantages over zooms. They are generally smaller and lighter, with wider maximum apertures and superior image quality. An ultra-fast (eg. f/1.8) 50mm lens is perfect for low light, 85-105mm is ideal for protraits while a fast 300mm (or longer) tele lens is a popular addition to any wildlife or sports shooters kit.
Standard Zoom
Most DSLRs come with a standard zoom - that is, one which spans from moderate wideangle to short telephoto. These "kit" lenses are find for most purposes, but there are alternatives that offer superior image quality and/or wider maximum apertures - at a price premium, of course. Look out for those with constant maximum apertures, which don't decrease as you zoom in.
Widee-Angle Zoom
Wideangle lenses make subjects seem further away, enabling you to get more in the shot – perfect for landscapes and architecture. Among the most popular wideangle zooms lens are the 10-20mm / 12-24mm and 17-35mm ranges. Superwide lenses cause more distortion, especially when tilted off the perpendicular, but can also create a great sense of drama.
Telephoto Zoom
Telephotos lenses make subjects appear closer. They are great for sport and wildlife where you cannot get close, while short teles are good for portraits. Telephotos magnify camera shake, so consider one with Image Stabilisation if your camera does not have it, or buy one with a wide maximum aperture. This way you won’t need to increase your sensitivity in camera, which can lead to noise.
Super Zooms
Want a one-lens solution for your photography? Get a superzoom. While they rarely compare with shorter range lenses in image quality, a 18-200mm type lens offers the benefit of speed, convenience and a dust-free sensor. Good for general shooting at moderate print sizes, but don’t expect to be making pin-sharp, aberration-free prints at exhibition size.
Macro Lenses
Many lenses misleadingly sport the “macro” moniker, but a true dedicated macro lens lets you get close enough to reproduce your subject at life-size (or half life-size) on the sensor. Macro lenses (few of which zoom) come in a range of focal lengths, from standard to telephoto, and can even be used with extension tubes for greater magnification.