Reversing Ring for Macro-Close Photography
Ordinary lenses can be used for macro photography by using a "reversing ring." This ring attaches to the filter thread on the front of a lens and makes it possible to attach the lens in reverse. Excellent quality results up to 4x life-size magnification are possible. When used with extension tubes or bellows, a highly versatile, true macro (greater than life size) system can be assembled. Since non-macro lenses are optimized for small reproduction ratios, reversing the lens allows it to be used for reciprocally high ratios.
To determine the reverse ring required, keep in mind the reverse ring fits into the filter thread on the front of the lens (not the focal length). The filter thread is often printed on the edge of the lens barrell, on a filter ring, and sometimes on the reverse side of a lens cap. If still not sure, check the owners manual or specifications on-line.
At extreme close up distances, the easiest way to focus is to move the camera forward until the image in the viewfinder is sharp. Exposure may be set on manual or aperature priority automatic.