As mentioned in earlier posts I rented the Sigma 150-600mm f/5-6.3 DG OS HSM Sports Lens for Canon EF and the Sigma 180mm f/2.8 EX DG OS HSM APO Macro for Canon EF to use on my Sony A7 III with the Sigma MC-11 adapter. I had heard on a “The Camera Store” video that the MC-11 paired with Sigma Canon mount lenses was practically equivalent to native e-mount lenses with respect to autofocus on A7 cameras. The only caveat was that the Sigma lenses for which this was true were restricted to three series, the Art Series, the Sports Series and the Contemporary Series. Unfortunately for me I was interested in the Sigma 180mm f\2.8 macro lens which is not in any of these series. So I rent ed this lens and the 150-600mm sports Series lens to compare how they performed with the MC-11. I can now confirm that the lens series that are specified by Sigma for use with the MC-11 do indeed autofocus with Sony A7 cameras utilizing all the various capabilities of the autofocus system of the Sony A7 III (at least as far as I was able to determine). And unfortunately, I can also confirm that lenses that aren’t in those sanctioned series of lenses have much less autofocus capability than those that do. Many functions such as autofocus while remaining in magnified view don’t work at all. As far as the accuracy of the autofocus it’s not as clear whether the capability of the lenses differ that much because I was using it as a macro lens and that type of lens usually doesn’t autofocus as quickly as normal lenses. My sense is that it is less capable. It feels like the autofocus that was available on the first generation of A7 cameras.
But the main message of this post is if there are Sigma lenses that extend the lens range for the A7 cameras in one of these three lens series (Art,Sports, Contemporary) you can expect to get near native autofocus capability with the Canon mount versions on the MC-11 adapter.