It has been one of the hardest of the Canon EF mount lenses to electronically adapt. In my opinion not so much because of the motor but because it is very sharp. It has become compatible with the SIGMA 150-600mm F5-6.3 DG OS HSM | Contemporary for SIGMA, that has the latest firmware Ver.1.03. This I fully agree with - but I have the feeling that Sigma having been the only serious manufacturer of an electronic EF-L adapter has been letting the L-Mount side down somewhat - this could be more especially obvious if some EF bonus lenses are compatible on the MC-11 and not so on the MC-21. I would have found this easier to accept if there had not been some fulsome praise in the past for the compatibility of the Sigma MC-11 adapter which I don’t ever remember being put as “great with Sigma EF lenses only”. I don’t remember anyone ever mentioning that it was not compatible with any particular Canon EF lens. As far as the bonus lenses were concerned the bonus lenses did not have limitations.

Glass I tested on. Canon ef 28 f1.8, Canon ef 50 f1.4, Canon ef 85 f1.8, Canon ef 17-40 f4, Tamron 24-70 f2.8 vc, and Tamron 70-200 f2.8 vc. I already shared my experience for birds in flight ( read the Red Kites article here) where I got an overall 50% keeper rate with the A7r II and 60% with the a6300, which I consider quite good. A6300, 1/2000, f/8, ISO 800 – 150-600mm Contemporary I have been puzzled by comments that the MC-11 has worked very well with EF lenses in general and I would have liked to know if it were more widely compatible with non Sigma EF mount lenses than the MC-21 was. For if it is as short on bonus lenses as the MC-21 is then it would only work on a relatively few “modern” Canon EF lenses. In my test of twenty Canon EF lenses on L-Mount it only supported 11 of them and two of them were MF lenses therefore for AF purposes the bonus was 9/18 or 50%. With lenses that are not compatible with the MC-11, it has corrected the release time lag which occurred during flash photography. *2 However when the variation in speed and distance is more substantial, the camera has more difficulty with continuous AF and continuous shooting. During the Tonfanau motorbike race, the AF simply couldn’t follow the bikers exiting from a corner or coming in a straight line. It progressively loses the focus point. I got an average keeper rate of 30% with both cameras with the a6300 performing marginally better. I tested all the Area modes and tried different settings like Balanced Emphasis instead of AF priority but the results were always the same. The areas that work best are Zone and Expand Flexible spot. Both the A7r II and a6300 lose focus progressively as the subject gets closer when shooting in burst mode.

In the end, it is a solution: not the best but at least you have one if you already own these lenses and want to keep using them or if you need them while waiting for Sony to release an equivalent. I think that among all the adapters available, this is definitely the one to consider right now (for Sigma lenses especially): it is one of the most complete solutions with a reasonable price tag. I hope Sigma will bring compatibility with more lenses in the future.

Keep in mind that the LED indicator light did not illuminate when I attached the Canon lens meaning it is completely non-compatible with the firmware of the converter. With that being said, using a Canon lens with the MC-11 is not outside the realm of experimentation. Just proceed with caution. The only limitation I find annoying is that you can’t force the camera to use phase detection points only. It selects which system to use automatically (like with E-mount lenses) and can slow down the speed in Single AF where the camera seems to prefer contrast detection. I'm not comparing to "most other adapters". I'm comparing to the Metabones adapter. Can you point to anyone who has done a comparison of the two and concluded that the Sigma adapter has wider and better compatibility than the Metabones adapter?

SIGMA MOUNT CONVERTER MC-11 Firmware Update

Ah, I was confused by this sentence, "I strongly suspect that the other adapter vendors have much more experience in Canon EF lens protocols."

L'eccellente Canon L 16-35 f/2.8 USM III ha nitidezza eccezionale anche a tutta apertura e questa risulta perfettamente mantenuta sulla Sony a7: anche gli angoli estremi sono ineccepibili. Before updating SIGMA MOUNT CONVERTER MC-11 firmware, please ensure you update SIGMA Optimization Pro to the latest version. Some older Tamron lenses apparently don't work on it at all. I guess those are victims of incompatible reverse engineering of EF protocols relative to what Sigma has done. I have not found any Canon lenses that didn't work on it, but I haven't tried that many. I do have a Tamron 24-70/2.8 G1, and that works fine on the MC-11.

Sigma MC-11 Mount Converter | SnapShot

So the quiet L-Mount forum has steadily become quieter and there seems almost zilch interest in adapting EF mount lenses there. The MC-21 has done its job thoroughly and most of the talk is now about what new L-mount lenses are being released. Fixed a problem in which the MF assist function would not work in rare cases when a lens with the MF switching function (Manual Override) enabled, or a lens with the focus mode switch set to MO was attached. So, that's the innocent explanation of why the MC-11 does not have such good support for Canon EF lenses,