Zoom lens

Two types of zoom feature on digital cameras: digital zoom and optical zoom.

Digital zoom simply crops an image to the centre - similar to the way a software image editor works. For example, when a user zooms in to take a picture at a magnification level of 2X (more on this below), the resulting image will have half the resolution of the original. In other words, the pixels that would have been used to capture the original or "un-zoomed" image are simply magnified. To compensate for the loss of actual pixelation, digital cameras then use a process called "interpolating", which adds pixels to the zoomed image using a complicated algorithm. The resulting image, however, is still far less vivid and effective than if the actual pixels had been used.

On the other hand, an optical zoom magnifies the image using a real multifocal-length lens. This means that the lens is actually magnifying the focal length and zooming in before the image is captured in pixels (the focal length is a property of the lens that dictates the amount by which it magnifies the scene).

The amount of this magnification is expressed in degrees, such as "2x" or "3x". A "2x" optical zoom, for example, means that if the camera's minimum focal length is 50mm, then it has the ability to take pictures up to 100mm.

These days pretty much every camera comes with at least 3x optical zoom. This is more than adequate for day-to-day use, but more serious photographers may want to invest in a more advanced model, that has a zoom lens of 6x or even 12x. Take note, if you buy an SLR, the zoom won't be measured in degrees like it is on a compact unit. Instead you will get a measurement for that lens, for example 18-55mm, but you can easily work out the comparable level by doing some simple maths.