What is a zoom lens and why should you use one?
Until fairly recently, when you bought a camera it would most likely have come with a fixed focal length lens. This means, basically, that the magnification it gave was the same and could not be changed (or, if it could, it would be fairly crude).
This was fine for most simple situations and served as an optimum magnification to be able to take standard shots.
But, if you wanted to get nearer to a subject, you had to use your feet or had to buy an additional telephoto lens. This would magnify the subject so that you appeared closer than you actually were.
Similarly, if you wanted to see the wider aspect of your subject, you would have had to step back or get a wide-angle lens. This would make your subject look further away than it really was.
Zoom lenses were developed to be able to change the magnification by using simple controls on the lens. A telephoto (or long) zoom would typically magnify the subject, as you saw it, from normal to larger in this way you could appear closer to the action. A wide-angle (or short) zoom would move you back from your subject in this way you could appear more distant from your subject and see a wider view.
With both types of lenses, you could choose all the steps of magnification in between.
Now virtually all cameras come equipped with a zoom lens this includes compacts and cameras for the more serious-minded. These zooms are typically a compromise and incorporate both wider angle and short telephoto setting and are usually of very reasonable quality.
Eric Hartwell runs the photography resource site http://www.theshutter.co.uk and the associated discussion forums as well as the regular weblog at http://thephotographysite.blogspot.com
