What Does 18X Mean on a Camera?by Kyle Horner
If you look at most modern, digital cameras you will find a number like 3x, 10x or 18x. These numbers represent the "zoom factor" of the camera. Zoom is simply the ability of the camera to magnify the subject in the viewfinder.
A zoom factor is really a ratio. If a camera has a zoom factor of 18x, it is able to magnify the subject by a ratio of 18 to 1. This means that at the highest setting the subject will appear 18 times closer than at the lowest setting. Since the starting point (or lowest setting) may differ between cameras, two cameras with the same zoom factor may appear to magnify by slightly different amounts.
Optical vs. Digital Zoom
Often digital cameras have two zoom factors; one for the optical zoom and one for the digital zoom. When you use the optical zoom, the lens physically changes position to magnify the subject. Optical zoom allows you to get closer while preserving the quality of your image. When you use digital zoom the camera simply crops and enlarges the center portion of the image. In this process the data recorded in the image is distributed over a larger area, which causes your image to lose quality.
Many camera manufacturers compare their zoom factors with 35mm equivalents. This number represents the focal length of a traditional SLR camera lens that would have the same capacity to magnify the subject. For example, one current Nikon camera has a zoom factor of 24x with a 35mm equivalent of 624mm. This means that a traditional SLR would require a lens with a 624mm focal length to magnify a subject the same amount as this digital camera.