Macro Photography Techniques - Part 3

The 3rd installment of the series will cover the use of extension tubes. Again this is a method which requires an extra piece of equipment, but again it is something which can often be acquired quite cheaply.

Macro Photography Techniques

1. Close Focus Lens
2. Teleconverters
3. Extension Tubes
4. Reversed Lenses
5. Macro Lens
6. Combining Techniques
7. Close Up Filters

Extension Tubes with a Fast Lens

First off, lets talk about what extension tubes are. Extension tubes are a simple device which mounts between the camera body and the lens. They contain no optical elements (where a teleconverter does). All they do is modify the register distance (distance from the lens to the sensor or film plane) which means the minimum focus distance of the lens becomes much less, as does the maximum focus distance for that matter. You can no longer focus to infinity with a lens mounted on extension tubes. Moving the lens further from the sensor or film plane also results in a loss of light. This is why I recommend using a fast lens when using extension tubes. The exact amount of light you will lose will depend on the thickness of the tubes (or how far from the sensor plane you move the lens).

Types of Tubes

There are 2 main types of extension tubes. There are those which operate the lens' aperture mechanism, and those which do not. The most commonly found is the type that do not. These are often sold very cheaply on ebay, and come in 5 parts. A body mount, a lens mount, and 3 extensions of various sizes. These work just fine, however, if you want to stop the lens down (and you will, to get more depth of field) these can become quite hard to use. If you stop down the lens, you will notice the view finder darkens significantly, to the point where focusing, and even just composition of a shot becomes hard or even impossible.

I recommend spending a little extra on your extension tubes, and getting the "Auto" type. This means that the extension tubes allow the camera body to still operate the lens aperture through the tubes. This allows you to focus/compose the shot with the lens wide open (as happens with the lens mounted normally) and then the body closes the aperture just as the shot is taken. I have a set of these extension tubes, made by Vivitar for Pentax K mount.

Bellows?

Bellows, what are they? Bellows are basically a very large, length adjustable extension tube. They allow for heaps of magnification, but are heavy and awkward to use. I have not personally used a set of bellows, nor do I see myself using a set of bellows as I like to be mobile. However, keep them in mind.

Which Lens

As mentioned earlier, I recommend using a fast lens which extension tubes, as it allows you to focus and compose more easily after you have lost light from the tubes themselves. Something to keep in mind is, the shorter the focal length of the lens, the more magnification you get from an extension tube. For example, my extension tubes are sized as follows; 12mm, 20mm and 36mm. If I use the largest tube (36mm) with my 50mm lens, I get extra magnification, but if I use the same tube with my 28mm lens, I will get greater than 1:1 magnification! A good approximate rule is, to get 1:1 use the same length of extension tubes as the focal length of the lens. This guideline only applies to lenses which are not extremely close focusing already (like the CZ Flektogon 35mm f2.4 which already focuses to 1:2 magnification, 35mm of tubes will get greater than 1:1 on this lens).

I have successfully used my 50mm f1.7 lens, 50mm f2.0 lens and 28mm f2.8 lens with extension tubes.

Focusing

As before, focusing is best achieved by moving yourself and the camera and lens closer to, and further away from the subject as required, rather than using the focusing ring. See Part 1 for a full description.

Results

Here are some photos taken using my extension tubes. Dont forget to share yours in the comments

50mm f1.7 lens, all 3 extension tubes, ISO 100, 1/180 sec, f11.0, onboard flash. These are aphids, the big one is an ant.

50mm f1.7 lens, 36mm extension tube, ISO 100, 1/180 sec, f11.0, onboard flash