How good are the images?
In general, lens converters for digital cameras perform surprisingly well when used with digital cameras in the 3- to 5-megapixel range. Most deliver good enough image quality for 4x6, 5x7, or even 8x10 prints. When shooting at maximum aperture, however, there may be slight softness at the edges and corners of the frame, and most wide-angle converters do exhibit some barrel distortion. Some converter lenses, like the Nikon optics (left), are big, and may block the camera's viewfinder and pop-up flash. As a class, screw-in converters by camera manufacturers for their models perform better than generic converters made by independent manufacturers-hardly surprising, since they are matched to specific lenses. But, these differences are smaller than I expected and I found only one sub-par performance: a magnetic-mount wide-angle converter (sold under the Bauer, Phoenix, and Sunpak labels) on a Canon PowerShot SD100. Other defects, such as color fringing, were not objectionable until the prints were enlarged to 11x14 or greater. Conclusion: Converter lenses for digital cameras are worthwhile and cost-effective in extending optical versatility, and they perform well enough for all but the most critical shooting applications.
Operational pluses and minuses:
Plus: Secure, precise mounting, less light falloff, close focusing not impaired.
Minus: Relatively large, some heavy enough to affect camera balance, may require adapter rings.
Plus: Secure mounting, little light falloff or focusing restrictions.
Minus: Camera bulkier due to bracket, mounting takes extra time.
Plus: Quick, easy mounting, converters very light and small, may mount on more than one camera.
Minus: Permanently mounted magnetic rings must be precisely positioned, are hard to remove, some noticeable falloff in corners/ edges with certain camera/converter combinations.
CLOSE-UP CAVEAT: Shot at left, zoomed to the max with no converter, is tack sharp. Right-hand shot with teleconverter added gets you closer, but focus is a tad soft. Moral: Don't use teleconverters at or near minimum focus distance - back off a bit.
TELE TERRIFIC: At normal distances (25 feet) maximum zoom, no converter shot (left) and same shot with 1.5X converter added (right) both show excellent detail. Wide-angle converters add barrel distortion, may show a touch of color fringing in big blowups.