Another strike against them is that they introduce additional aberrations. Even the best made, highest-quality TC has some level of imperfection. So adding a TC to a lens is adding flaws. If you use one you’d better prepare for at least a modicum of image deterioration.

(Left): The Olympus Zuiko Digital ED 300mm f/2.8 telephoto. It has a marvelous way of turning the background into a pleasant blur. (Right): By adding an Olympus EC-20 to the 300mm f/2.8 telephoto we bring the subject closer without significant loss of sharpness. Both shots were made from a tripod.

And TCs are not cheap; they range in price from $200 to $500 with a fair number clustered around the $400 level. That’s nearly the cost of a complete lens. So, is buying a TC Buying Smart?

The proof of the pudding, as they say, is in the performance. And the performance delivered by the Canon and Olympus TCs used in this survey was remarkable. When the Canon 2x doubled the Canon 70-200mm f/4L zoom, it was nearly impossible to tell which images were shot with the converter and which without—they were that sharp. The Olympus TC performance was equally impressive.

Particularly in those situations where you need a long, long telephoto and already have a medium long one, a TC is the right choice. On the other hand, if you’ve just been hired to shoot sports photography and need long, bright telephotos every weekend, buy a new long lens instead. If you are a Four Thirds system user, you’ll get a lot of bang for your buck out of an Olympus EC-20 because you can—and will—use it with every lens.

This is a shot with the Olympus Zuiko Digital ED 8mm f/3.5 fisheye and the Olympus EC-20 Teleconverter.

Then there’s that third category—the rabid hobbyist who’s willing to sacrifice a little perfection in exchange for fun and excitement. Adding a converter to a 300mm lens is thrilling. It makes you glad you own a stout tripod. And it opens doors to photographing subjects (birds, the moon, etc.) that you may be missing now. Branch out with a TC and if you discover a new passion you can upgrade to a longer lens later.

You can read Jon Sienkiewicz’s Blog at: www.shutterbug.com.