Old sigma 1.4 ex apo dg converter vs Canon 1.4 mk3
i use the converter on a tamron sp vc 70-200 2.8 .i also have the canon 1.4 extender mark 3 and have found that the canon extender sometimes does not focus well it sometimes judders and focuses slowly.image quality wise after doing several lens tests i can find no visible difference
between the sigma and canon 1.4 converters.The old sigma converter is a great performer and a bargain,but on the tamron 70-200 be sure to dial in 1 stop of exposure comp.