10.08.12

Photography Monthly's tip week: Making the most of macro, Tip 5

It’s Friday, it’s nearly the weekend and so today brings about the conclusion to our Making the most of macro themed tip week.

Today's fifth and final tip is experiment with extension tubes:

Let’s face it, in our current economical crisis we can’t lavish our cameras with new lenses and upgrades anymore – for those who ever could!

Macro lenses can pack quite a punch where our wallets are concerned and so it’s a good idea to come up with an alternative to good macro photography, without splashing out hundreds of pounds on a new dedicated lens. This is where extension tubes come in.

Macro extension tubes are devices that add high magnification capabilities to virtually any camera lens. This can give a whole new range of subject matter to your existing camera equipment.

So let’s see whether an extension tube would be suited to you.

Explaining the extension:

An extension tube is simply a hollow cylinder that fits in between your camera and lens, causing the lens to move further from the sensor. This additional distance allows your lens to focus more closely, which in turn provides more magnification capability. Unlike most lens accessories, extension tubes don't add any extra optics, and are therefore relatively inexpensive and simple devices.

An extension tube increases lens magnification by an amount equal to the extension distance divided by the lens focal length. For example, adding a 25mm extension tube to a 50mm lens will give a magnification gain of 0.5X.

All camera lenses have some amount of native extension, which is used to focus on everyday objects. Lenses with closer focusing distances usually have more native extension, but these will also benefit less from extension tubes.

An extension tube is usually specified in terms of its extension length in millimetres. Most manufacturers provide a range of extensions from 8-35mm, although multiple extension tubes can be stacked to increase the extension even further. Examples include the Canon 25mm EF II, the Nikon 8mm PK-8 and the Kenko DG 12mm, amongst many others. Extension tubes also usually include basic electronics to pass through signals between the lens and the camera body (such as for autofocus).

Consider this:

Image quality shouldn't be a factor when deciding between different brands of extension tubes as they all use the same low dispersion air. However, build quality may be an important consideration — particularly if you plan on using it with a heavy telephoto lens. Additionally, older extension tubes don't always work with newer lenses designed for cropped SLR sensors.

The pros:

*Much less expensive than purchasing a dedicated macro lens.
*Provides a flexible and upgradable increase in magnification with virtually any camera lens — even existing macro lenses.
*Doesn't place additional glass elements between your subject and your camera so thereby minimising any potential loss in image quality.
*Provides consistent, predictable quality regardless of extension tube brand.

The cons:

*Provides only a minimal magnification gain with telephoto lenses.
*Causes your lens to lose the ability to focus on distant objects.
*Causes your lens to focus more closely than it was designed and so high magnification images will therefore usually have lower quality than with a dedicated macro lens.
*Requires that you remove your lens from the camera each time you wish to change the amount of extension, which can raise the risk of dust settling on your camera sensor.
*With zoom lenses, the image can go quickly out of focus as you zoom in or out.

If any of the above disadvantages has the potential to be a problem, it's worth considering using either a dedicated macro lens or a close-up filter. If the pros outweigh the cons then browse the big names’ wide array of extension tubes and see what suits you, your camera and your style of photography.

As a weekend project, why not experiment with some extension tubes and send your photos into our gallery and they could end up featuring as our photo of the day!
 

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