Accessory Lenses For Digital Cameras

There's a great way to make your digital camera more versatile without spending an arm and a leg. Thanks to accessory lenses, practically any camera can be made to handle close-ups, wide-angle shots and even telephoto zooming—well beyond the camera's built-in capabilities.

Though many digital cameras offer an excellent zoom range, you may want more to produce a specific photograph. If you want to create an expansive scenic image, attach a wide-angle adapter. Connect a telephoto adapter so you can capture a shy bird at a feeder. Within moments of attaching an accessory lens, a wealth of photographic opportunities can open up.

Lens Options

Lens accessories break down into three major categories: wide-angle, telephoto and close-up lenses.

Wide-angle lenses turn "normal" focal-length lenses into wide or super-wide lenses. The average wide-angle focal length on today's compact cameras is approximately 38mm (35mm equivalent). Such cameras are lacking true wide-angle capability, but the use of these inexpensive accessory lenses makes wider perspectives possible.

Telephoto lenses convert standard or telephoto-length lenses into moderate or super-telephotos, depending on the power of the lens to which it's attached. Much like teleconverters on an SLR lens, these add-on lenses make it easy to fill the frame with your favorite subject—even if you can't move any closer to it.

Close-up lens adapters allow you to achieve professional-looking macro and detail photographs. Unlike a filter, which would simply screw on the lens' front element, these adapters are designed to match optically with the primary lens. Several different lens elements are incorporated into their design to maximize optical quality.

Understanding Magnification

The strength of accessory lenses is measured in power, or magnification. Just as your camera's 2x focal-length zoom lens doubles the image size when adjusted from wide to telephoto, a 2x accessory lens will double it again. A 0.5x or 0.7x wide-angle lens will reduce the effective focal length of your lens by half or three-tenths, respectively.

To determine your new focal length when such an accessory is attached, multiply the magnification number (the 2 in 2x or the 0.7 in 0.7x) by the focal length of your lens. For example, a 0.7x wide-angle adapter is connected to a camera with a 38mm lens (35mm equivalent); the lens becomes a 26.6mm lens. A 2x adapter on a 105mm focal length doubles it to 210mm.

Close-focus attachments decrease the camera's minimum focus distance and increase magnification needed to capture fine details in objects. Close-up lenses are designed to work best at specific distances from the subject.

Filter Fittings

Though some models provide a convenient filter thread to attach lens accessories, others may require an adapter to accommodate accessory lenses.

Cameras that provide a filter thread will allow filters and accessories to screw on directly to either the lens or the camera body. Some threaded mounts are very small in diameter, so they may require a step-up ring to accommodate filters and lenses; that's an in-between coupling that allows larger filters to screw on to smaller lenses.

Other cameras use a snap-on or snug-fit adapter. This type of adapter provides the means for the accessory to fit securely to the camera. They may screw into a tripod socket, squeeze around a lens barrel, or even clip on to the camera body. (Check with your camera's manufacturer to determine which adapter is recommended for your particular model.)

Macro

The "power" of a close-up lens measures how much magnification the lens will provide. Therefore, a +4 won't give as much magnification as a +7, which isn't quite as powerful as a +10. (The actual mathematics states that the magnification of a lens equals one divided by the focal length in meters. Just remember that the bigger the number, the greater the magnification.)

Perhaps the best thing about close-up attachments is that they can be stacked for even greater image enhancements. Sure, with every lens you place between the subject and your lens you're cutting out more light. But if you're shooting on a bright sunny day or with a flash, you shouldn't have anything to worry about. You can take that +7 and add it to the +10 to create a +17 lens that will get you really close to that little detail you're so wanting to capture.

Accessory Lens Tips And Tricks

1 If the viewfinder is blocked by the accessory lens, compose your pictures by looking at the LCD. This will ensure that you can see exactly what the CCD will see.

2 Be careful when using an on-camera flash. With close-up lenses, there may not be enough distance between the flash and the subject for even illumination. If you're using a large lens adapter, you could see a shadow cast from it on your scene.

3 With wide-angle attachments, make sure your camera's lens is set to the full wide-angle position to maximize the widening effect.

4 For your telephoto attachments, set the camera's zoom lens to the maximum telephoto focal length.

5 Consider using a tripod with telephoto attachments since camera movement and normal vibrations will be magnified along with the view of your subject.

6 If needed, adjust your camera's exposure compensation if the accessory lens starts to fool the auto-exposure function.

7 Always carry a cleaning cloth or lens tissue and an anti-static brush. Periodically clean the lenses and remove dust, debris or fingerprints. Such contaminants will accumulate and reduce image quality.

8 Don't toss the accessory lenses into your camera bag unprotected. They're usually sold with a carrying case that will keep them from getting nicked and scratched by your other gear.

9 Don't use close-up lenses in combination with wide-angle or telephoto conversion lenses. Your camera might not be able to focus properly and image quality will suffer.

10 Experiment. You'll learn what you can and can't get away with—whether that's using a flash with your lenses, combining lenses or maximizing the effects of any particular attachment.