2:1 magnification

I picked up a set of super inexpensive Pro Optic Extension Tubes. They feel pretty cheap and I doubt they’ll last for years and years, but they come with electrical connections at half the price of the Opteka, a third the price of the Kenko, and a hell of a lot cheaper than Canon’s.  If I could afford the Kenko tubes, I’d probably have gone with them, since they’ll last a lot longer, but as long as they keep the lens on the camera and pass through information to stop down the aperture, extension tubes don’t need to be fancy.  There’s no glass in them: they work by moving the lens farther from the sensor, so it projects a larger image.  It’s a lot like a film or slide projector, where the farther it is from the wall, the larger the picture.  But dimmer too: you have a fixed amount of light making up the image, and the larger that image, the ‘thinner’ it’s going to be.

We’re covered in snow and slush here in Boston, so my macro expeditions have been limited to the far corners of the kitchen, where I found the exotic Chlorophytum comosum: the spider plant.  With the 100mm f/2.8 USM macro lens, the full set of tubes gives about 2:1 magnification.  At this point, you really need buckets of light in order to get an aperture with a reasonable depth of field: my flash was set to 1/4 power and was only a few inches away.  Unlike bugs, spider plants don’t run away from the camera, so I used a tripod to make these a bit easier.