Review on Canon Telephoto Extender Super Lenses by Barbara Lawler

I upgraded my 1.4x II lens to use with a 70-200 f/2.8 II lens and it impressed me, apart from one optical flaw. At 70mm it actually shows more CA/margin than the previous model. However, at 200mm it performs better in this regard with less CA/fringing. I actually sent back the first one Revane sent me, thinking it was somehow damaged. The exchange went the same way. I think since these Mark III converters were designed for use with super telephoto lenses, the optical design was made to maximize IQ at these focal lengths. At the broader end, it might not correct for those aberrations either, although it does offer higher resolution throughout (see below). In terms of sharpness, 1.4x III is better. I carefully compared and took side-by-side test shots. Tripod, mirror lock-up, real-time focusing, etc. The 1.4x III has always featured more detail and greater contrast. It was actually quite noticeable, although not as much when photographing in the real world. Autofocus performance is the same (with this lens) but I like the build quality better. More mounting screws, a better lens release switch, etc. I think the upgrade was worth it to see the extra resolution it offers. I am very happy with it.