Alternatives to the macro lens: Part 2
Macro lenses are all very well, but they're expensive and specialised (though they can be used a normal lenses too). Fortunately, there are less costly alternatives. I covered two of those options in Monday's blog: accessory lenses and reversing rings (if you've not read that blog, have a look here and come straight back). Today I'm going to talk about extension tubes and accordion bellows.
Kenko extension tubes – a three-section, automatic set of extension tubes. Available for most camera mounts.
An extension tube is exactly what it sounds like. It's a tube that's placed between the camera body and the lens to extend the distance between the two. This extension allows the lens to focus more closely than it otherwise could. There are no optics in the extension tube so there's no degradation in image quality.
However, you really need to use the best lens you can with an extension tube. Any flaws in a lens are magnified, so a less-than-perfect lens will produce even less-than-perfect results when fitted to an extension tube. For this reason it's a good idea to use a prime lens with extension tubes; zoom lenses tend to be more comprised optically than primes.
Depth of field can be a big problem when shooting close-up. You either need to use very small apertures, or as in this image, focus precisely on the part of the image you want sharpest.
Extension tubes come in two forms. You can buy extension tubes that are just one tube or extension tubes that can be quickly broken down into several shorter tubes of varying lengths. The latter is the more flexible option as this allows you to shoot at a number of different magnifications by altering the number of tubes you use. Another way extension tubes differ is whether or not they carry a signal between the camera and the lens.
Those that don't are cheaper but are less convenient. As with reversing rings this means that you can't use autofocus, automatic metering or change the aperture unless the lens has an aperture ring. For the relatively small difference in price I'd always go for extension tubes that do carry a signal between the camera and lens.
Museums are good places for macro photography (as long as they allow photography that is). Keeping your lens lightly pressed against glass display cases helps to cut out distracting reflections.
Bellows are the flexible cousins of extension tubes. Like extension tubes, bellows extend the distance between camera and lens. This is achieved by fixing the lens at one end of a set of bellows and the camera at the other. The length of the bellows is adjusted by stretching or compressing them along a guide rail. This means that image magnification can be very finely adjusted. This fine-control does come at a price however.
New sets of bellows tend to be far more expensive than extension tubes and not that far off the cost of a macro lens. Fortunately, there are a good number of bellows available second-hand that use the M42 mount. This is an old mount type that is can be readily adapted to fit proprietary camera mounts like Nikon's F mount and Canon's EF standard.
When shooting objects close-up you also magnify the size and visibility of dust on the object. It pays to clean this off before you shoot rather than clone it out in postproduction.
One problem common to both extension tubes and bellows is light loss. The longer the extension, the greater the light loss. If you're using automatic metering your camera should automatically deal with this. If you're using Manual exposure (or using a hand-held meter) you'll need to be prepared to use a longer shutter speed, higher ISO or larger aperture than you'd expect.
Any of the four options described are a viable entry to the world of macro photography. The problem you may find is that macro photography is strangely compelling. Once you start, you may find it difficult to stop. Let me know how you get on!