Compared to a unifocal lens, a zoom has
several advantages. The following are some advantages of using a zoom
1. You can carry just one zoom lens on your camera and still have more
flexibility than three or four unifocal lenses in the same general
range would give you. Therefore, you can pay less attention to
equipment and more attention to taking pictures. You will be better
prepared for unexpected opportunities because you won't have to keep
fumbling for another lens.
2. Within limits you can control image size without moving the camera
position and thereby changing the perspective. However, if a
perspective change is desired, the camera can be moved and the image
size restored with the zoom control.
3. Without moving the camera, you can frame and crop your pictures in
the viewfinder for best composition - especially helpful with color
4. You can review the effects of various focal lengths on your subject
without actually interchanging lenses.
5. The image size of a moving subject can be kept under constant
6. Your camera can be placed at the best distance for balanced
synchro-sunlight flash and the image size can be adjusted to your
requirements by zooming.
7. Exploding "zoom" effects can be achieved with slow shutter speeds.
8. Even though not as convenient as a true zoom, a varifocal zoom is
faster and simpler to use than a set of three or four unifocals, which
would not only have to be interchanged, but would have to be refocused
each time as well.