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March 26, 2008

Other options for Macro Photography - Choosing a Macro Lens Part 2

Last week I talked about choosing a macro lens. This week I will review some other pieces of equipment you may use to get into macro photography. Bellows, extension tubes, close up filters (often called diopters) and reversing rings.

Each of these can be used to make photograph small items to some extent.

Bellows and Extension Tubes
Bellows and extension tubes both operate using the same principle. Moving the lens further away from the camera body will allow your lens to focus closer which means you can get the lens closer to your subject, and therefore, render the subject larger on your piece of film or digital sensor.

Extension tubes are similar to a lens but do not contain any glass and have a camera mount on one end and a lens mount on the other. To use them, attach the tube to the camera using the camera mount as you would a lens, then add a lens to the extension tube as you normally would a lens to a camera. Extension tubes may be stacked together for further magnification.

Bellows also have both a camera mount and lens mount. The difference is both mounts are attached to a rail system and flexible bellows that allows the lens and body to change distances between each other. By increasing the distance between lens and camera, you can increase or decrease your magnification factor.

Both have their advantages and disadvantages. Bellows units are larger and require more care so that the bellows unit remains flexible and free of light leaks. Extension tubes are solid so require less care but do not offer the flexibility of variable magnification of your subject. More expensive extension tubes and bellows units offer automatic aperture control allowing you to focus with the full availability of light before stopping down to take the photograph. Units that do not feature automatic aperture require lenses that can manually be stopped down which must be done prior to taking the photograph. With both of these systems, the further the lens moves from the camera, the less light you will have available with which to accurately focus and shutter speeds will be longer.

If your camera does not offer TTL metering (older, fully manual SLR's may not) there are some complicated formulas for arriving at the proper exposure settings for a given magnification that are well beyond the scope of today's tip.

Close Up Filters
Close up filters also allow you to move in closer to your subject. They are essentially small magnifying glasses that screw on to the front of your lens. These are relatively inexpensive and provide a decent quality image for the price. Close up filters are a good option if macro photography is something you do only occasionally and wish to keep your costs down. They are available in a variety of magnifications and do not require any additional exposure. Close-up filters may be stacked for increased magnification.

Lens Reversing Rings
A lens reversing ring offers the least amount of flexibility of any of the options I have talked about so far. This ring screws on to the filter threads of one lens and a second lens threads on to the reversing ring the same way. You end up with two lenses stacked together, front elements facing each other. The trick here is that you use a longer focal length lens coupled with a shorter (the longer attached to the camera body) to increase magnification. This is generally a very impractical solution. It is awkward, may put unnecessary amount of stress on the front barrels of the lenses and exposes your rear lens element of the furthers lens to possible damage. I have done this with a 200mm and a 50mm lens to achieve a 4:1 magnification though.

As with so many things in photography, there is more than one way to get a task accomplished. Macro photography is the same. I have talked about 5 different options today and in my last tip. What is best for you will depend upon your required quality, ease of use and budget. Sometimes, to get big impact photos, you have to think small.

Until next time, happy shooting.

Posted on March 26, 2008 06:52 PM | Permalink

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