I am looking to purchase a new digital camera. I know what I am looking for is in the 10x-12x optical zoom range if it is not an SLR. I also want to consider SLR cameras, but I do not understand how to compare the SLR lenses which are measured in mm to the cameras with have an integer multiple zoom factor. Help! Times is equal to the ratio of the longest and shortest focal lengths. Take the digital rebel XT. It comes with am 18-55mm kit lens (kit lenses suck for other reasons so you should buy a higher quality lens). That is roughly 3X zoom capability (55/18 = ~3).
Note that the focal length determines how magnified the object is. So when evaluating a lens for how much it is able to bring an object closer to you, it's the higher number that counts.
For example, my Sony DSC-R1 has a 24-120mm lens. This is 5 X zoom capable. However, the amount of magnification this lens provides over the XT is more than double (120 vs 55).
A camera that is higher zoom, does not necessarily have more telephoto capability as a camera with a lower zoom. Look at the focal length. Yeah he is correct the larger focal length divided by the shorter focal length gives you zoom factor.(larger fl/smaller fl=zoomfactor of the lens). | 