WITH AND WITHOUT A TC:
To confirm our opinions on teleconverter performance, we tried one of this month's test lenses—the Canon 70–200mm f/2.8L IS II—with and without Canon's matched Extender EF 1.4X III ($500, street). Setting the lens to 135mm, its SQF score for sharpness and contrast dropped insignificantly—still an Excellent rating. In fact, the 1.4X 135mm score was noticeably better than the lens alone at 200mm. SQF did drop off to Good at 200mm with the converter (280mm effective), although this is typical of the dropoff we find in longer zooms that rack out to 270–300mm. Moreover, light falloff performance actually improved with the converter: There was no falloff, whereas the lens alone had to be stopped down to f/4 to eliminate light falloff at 135mm. Distortion also improved significantly, although with the teleconverter, it flipped to pincushion from barrel.