A lens that is considered a macro lens is one that has two main factors. The lens element is flatter than a normal lens and it has a focusing ring that allows closer focus than a normal lens. Most lenses of this type can reproduce an image at a ratio of 1:2. That means that you can have the image on the sensor or film that is ½ the size of the object in real life. Some have a 1:1 ration, which will put the exact real life size on the film or sensor. These lenses are made for a variety of uses. Nature photos of things like bugs and flowers are a popular use. Since the glass if flatter than a normal photo lens, it is best for taking photos of flat objects such as document, coins and stamps. Although this lens type was designed for these photography types, it can be used in normal photography as well. They don’t quite have the maximum f/stop of normal lenses, however. The same rule applies to the macro lens as with others, the focal length is based on a full-frame film or digital camera and must be multiplied by a factor based on the sensor size. Macro lenses come in sizes generally of 50mm, 60mm, 70mm, 80mm, 100mm, 180mm and sometimes higher or lower. Look for the word “macro” in the description. There are a few true zoom macros, but on zoom lenses if it shows macro, it means that you can focus closer than typically a similar lens without macro.