TECHNIQUE: Macro - quick and dirty.

So you want to shoot macro? But you don’t have a macro lens and can't justify the outlay? Get yourself some extension tubes.

What is an extension tube?
Essentially this is just a tube that fits between your camera and lens, thus extending the distance between your front element and the sensor.

This has the effect of enabling closer focus and greater magnification, but can cause a loss of light, which in turn will lengthen your required exposures (tripod suggested).

The further away from the sensor your lens is, the closer you will be able to focus.

Extension tubes come in a range of lengths and typically you can buy sets. Kenko do a set of 12mm, 20mm and 36mm that are handy and by stacking the tubes, you can get closer than you’d ever want!

Example:
The following shots show the effect on magnification and loss of light with the use of extension tubes of differing length. The lens used for this test is a Canon 50mm f1.8 lens and it was set at f2.8 throughout.


50mm, no extension @ f2.8, shutter speed 1/800 second


50mm w/12mm extension @ f2.8, shutter speed 1/640 second


50mm w/20mm extension @ f2.8, shutter speed 1/500 second


50mm w/36mm extension @ f2.8, shutter speed 1/400 second


50mm w/68mm extension (12mm + 20mm +36mm stacked) @ f2.8,
shutter speed 1/320 second

As you can see, the addition of even the 12mm extension tube has a huge effect on how close we can get and the larger the extension, the higher the magnification. What is also obvious here is that the more extension you use, the more light you lose, so be aware your exposures times. A tripod is a good addition to any macro setup.

Macro doesn't have to be expensive to start with, but be warned, it's a slippery slope!