I put my 300mm 4.5 FA zoom and teleplus2x convertor on my MZ-S and guess what autofocus was fast and very accurate. Better and faster than my tokina 80-200mm zoom. I then got a little excited and tried a sigma 400mm macro 5.6 and provided it was bright sunlight it worked about 50% of the time and funnily it picked up moving cars better than still objects. I then used it with my oldI was told by someone that two times convertors didnot work with lenses with a apetuire size of less than 2.8. Are the sigma apo 1.4x and 2x convertors good quality teleconvertors and will they produce good sharp contrasty images.?
