Extension Tubes

We hate to admit it, but when we first get interested in photography we almost immediately start dreaming of the day we own that 600mm F4.0 monster lens, and three pro camera bodies with 10 frames per second motor drives. Boy! If only we had that equipment, our photography would really improve. The truth is, most people can add three inexpensive accessories to their camera bag, and start getting publishable photos.

These items are not glamorous. They're small and inexpensive, but they can make the difference between an ok photo and a great photo. They are polarizing filters, cable releases and extension tubes. Most photographers I encounter in the field have polarizing filters and cable releases. Surprisingly, a large number don't carry extension tubes. The following is a summary of what these tubes can do.

Extension tubes:

An extension tube is just a hollow tube that extends the lens from the camera body. There are no glass elements in the tube, which makes them inexpensive, lightweight, and easy to carry. By attaching the tube between the lens and camera body you reduce the minimum focusing distance of the lens. Since there are no glass elements in the tube, there is no degradation in the optical quality of your lens.

The advantage of reducing the focusing distance of the lens, is that you can magnify the size of the image on the film. Extension tubes are often combined with macro lenses to provide additional magnification. For example: A 50mm or 100mm macro lens may be able to provide 1/2 life size images on the negative. With the addition of the extension tube, this lens can now provide a full, life size image.

Reducing the focusing distance of the lens can be very useful if you are using long focal length lenses (180mm and longer). For example: A 300mm lens may have a minimum focusing distance of approximately 9 feet. A 50mm extension tube could reduce the minimum focusing distance to about 5 feet. By using this combination you can nearly fill the frame with a monarch butterfly from 5 feet away. Many larger insects (butterflies, praying mantises, dragonflies, etc.) won't tolerate your presence at the distance necessary to fill the frame with a 100mm macro lens (less than 2 feet). However, these insects will tolerate your presence at 5 feet and the combination of a 300mm with extension will do the trick.

Extension tubes can be used with lenses in the 100mm to 200mm range to get great close ups of flowers and other smaller subjects. Typically, you can purchase these tubes for $30 to $100 depending on the brand (they can be considerably less if purchased second hand). This is a lot less than a macro lens, and it is easier to carry extension tubes, than it is to carry an additional lens.

Extension tubes can also be used for smaller animals like squirrels, birds, chipmunks, turtles, snakes, etc. In fact, this is a common technique among serious bird photographers who routinely use lenses in the 500mm to 800mm range. These lenses may have a minimum focusing distance of 20-25 feet. At this distance you cannot fill the frame with a sparrow-sized bird, even if you are using an 800mm lens. Bird photographers will use various approaches (primarily blinds) to get less than 20 feet from very small birds, and they will use an extension tube to allow the big lens to fill the frame with a small bird.

The sparrow photograph above was taken with a 500mm lens and a 25mm extension tube. The bird was about 15 feet away (which was below the minimum focusing distance of the lens). It would not have been possible to focus on the bird without the attached extension tube.

At many camp, or picnic sites, chipmunks will approach within 5-7 feet. If you are using a 300mm lens with an extension tube, you can get frame-filling shots of these very small critters. Also, many reptiles will require some additional working distance and this approach will do the trick.