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Extension Tubes for Close Focusing

Another good accessory for closer shots is a set of extension tubes. Extension tubes are simply tubes or spacers that fit between your removable lens and the camera body. The tubes have no glass, which makes them quite durable. They push the lens away from the sensor, which allows the camera and lens to focus closer, as seen in Figure 6. Extension tubes can let you focus at true macro distances, where the subject is the same size in the real world as it is on your sensor.

Figure 6

Figure 6 Evening primrose, zoom and extension tubes.

These tubes usually come in sets of 2–3 units. Like achromatic close-up lenses, extension tubes are a fraction of the cost of a macro lens. Kenko makes good ones for almost all brands of cameras and lenses. You can use them on all of your lenses, though they might not work well on your widest focal lengths. Be sure you get true automatic extension tubes that allow the camera and lens to communicate with each other for focus, f-stop control, and exposure.

Extension tubes allow your lens to focus close, with very high quality results, as seen in Figures 7 and 8. The result will vary somewhat depending on the lens, however, and it has nothing to do with how expensive the lens is. Some expensive “fast lenses” (such as lenses with maximum apertures of f/1.4 or so) were never designed for close work and often don't do well with it.

Figure 7

Figure 7 Fuchsia-flowered gooseberry, zoom and extension tubes.

Figure 8

Figure 8 Paintbrush, telephoto zoom and extension tubes.

Like achromatic close-up lenses, extension tubes change effect based on the focal length of the lens. They work in proportion to their size in relation to the focal length of the lens. For example, a 25mm extension tube has a very different relationship to a 50mm focal length than to a 200mm focal length; 25mm on that 50mm will get you much, much closer. You need more extension for longer focal lengths in order to get very close.

A challenge with extension tubes is that you have to take your lens off, mount an extension tube, and then put the lens back on. Every time you want to change the distance to your subject, you may need to change your extension tube. (You can first try changing the focusing ring on the lens, though.)

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