In the cool, calm morning air this beautiful Antheraea polyphemus moth stayed still for quite some time on the exfoliated bark of a Crape myrtle tree.
The moth was shot using a 20mm Kenko extension tube with a 70-200mm zoom. With the tube you loose the ability to focus at any normal distance so it's not nearly as versatile as a dedicated macro lens. The tubes are hollow, no glass, but do include electrical connections for the lens to talk to the camera body. No glass means no degradation of the lens optics. There is a reduction of light reaching the sensor and stacking tubes lowers the light further while increasing the enlargement. For manually focused shots from a tripod the light loss is easy to live with.
Another option for using an existing lens for macro photography would be to add a close-up filter to the front of the lens. There's no light loss with the filter. There can be softening of the image using modestly priced filters. The filters can also be stacked for greater enlargement and, like the tubes, you are limited to close-up focusing. For the greatest flexibility a dedicated macro lens like the 180mm macro is an ideal choice. Here's another early morning moth, a luna moth, shot with the same setup. -pw
