Ok, now we know how to care for a lens and why they are important. But what lens do I need? What lens you need depends in large part on what subject you want to photograph and under what conditions. Low light and night photography
call for fast lenses that allow for very large apertures
. If you want to take landscape images you will need a lens with a wide field of view. If you want to take wildlife photography you will most likely need a strong telephoto lens. The strength of a lens is measured in millimeters. This is marked as "mm" on lenses. Take a look at this gallery of images
to see what the "mm" markings really mean in terms of magnification.