Calculate a Macro Lens
Macro lenses are lenses that are described as having a 1:1 magnification factor. This means that the physical size of the object being photographed is equal to the size of the projected image on the digital sensor or film. These lenses are specially designed to capture the fine, intricate details of small objects. Not all macro lenses are created equal, however, and many designated with the "macro" name are not true macro lenses. To calculate your macro lens, use a simple magnification formula, plugging in values you collect from a test shot taken with your lens.
Instructions
1. Calculate the distance between the front of your lens and your subject, in millimeters, with your tape measure.
2. Determine the focal length of your macro lens. The focal length is typically printed on the lens itself and will probably be a value between 50 mm and 200 mm.
3. Divide the focal length of your lens by the distance between you and your subject minus the focal length. For instance, if you are 200 mm from your subject and shooting at a focal length of 50 mm, subtract 50 from 200 (150) and divide 50 by that number. In this case, the value would be 1/3.
4. Create a ratio to find your magnification factor. In the above example, the magnification factor would be 1:3, which means that the size of your subject is three times its apparent size in the camera. Therefore, the example lens is not a true (1:1) macro lens.
Tags: focal length, your subject, magnification factor, your lens, Calculate Macro, Calculate Macro Lens, distance between