It is as extensive as I an make it - there are a huge range of EF mount lenses in circulation - I can only do what I can but I do own more EF mount lenses than most. Nor am I going to buy more recent Sony bodies to test the compatibility further. If I were still in business and was asked for my advice I would have charged these guys a good size fee for some simple advice: that they badly needed an adapter that would make EF mount lenses very compatible on L-Mount bodies. If Sigma was not up to it they should have encouraged some third party to do so and made it easier by licensing the L-Mount body protocols for a nominal fee. I also know that Metabones and Viltrox adapters both work well for EF mount lenses on M4/3 - with Metabones being almost 100% compatible. But Sigma does not make an electronic adapter for M4/3. With the MOUNT CONVERTER MC-11, users of SIGMA SA-mount interchangeable lenses and SIGMA EOS-mount interchangeable lenses for Canon camera bodies* can use them as is with Sony E-mount camera systems. Users of multiple mounts will enjoy more flexible use of their valuable lens assets. Physically, I would say it's quite good. Well built, anti-reflective inside, solid, and with excellent tolerances (infinity is exactly infinity on lenses that have an infinity stop).

It has improved the compensation effect when it is used in combination with the Sony α9, Sony α7III and specific lenses*, and their in-camera image stabilization adjustment is set to AUTO. It has been set to I mainly use older L lenses (early zooms from c. 2005) and they work poorly-to-OK but the 1.2/50L is superb on the MC-11 with fast and accurate focus on A7r4.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. It has become compatible with the SIGMA 85mm F1.4 DG HSM | Art for SIGMA, that has the latest firmware Ver.1.01. It doesn't focus at the same speed as Sony native lens. Example: My Sony 24-70 f2.8 takes less than half a second to acquire focus. While the adapted lens takes at minimum half a second to a second. If that half a second is required for you. Than you better off getting the native lens. So, that's the innocent explanation of why the MC-11 does not have such good support for Canon EF lenses, but what about differences between the MC-11 and MC-21? Perhaps the origin here is the difference between translating E-to-EF and L-to-EF? Perhaps E has better facilities for adapted DSLR lenses, as it was designed to accommodate Sony's adapters to A lenses? Perhaps that means that the MC-11 is more forgiving of unsupported Canon lenses than the MC-21? Before we get into the performance of the MC-11 (which proved impressive) let’s have a look at some of the features which make the MC-11 a welcomed addition to the lens converter scene. Construction Quality and Features

It has become compatible with SIGMA interchangeable lenses for Canon*1 that are updated to firmware ver.2.00.While Sigma bills the MC-11 as a converter that enables Sigma Canon-mount lenses to be used on Sony cameras (including the superb A-series optics), naturally there’s a lot of interest from photographers with a collection of Canon lenses. With this in mind, I tested the MC-11 with the Sony A7R III and a collection of Canon lenses. The MC-11 converter of course works with the majority of Sigma’s glass including their Contemporary, Sport, and Art lines of lenses. At the time of this writing there are 22 total lenses which are compatible with the MC-11 and that number continues to grow. As it stands, only Canon EF mounts and Sigma SA Mount versions of the converter are available. Sorry Nikon users. For the rest, I can write the same thoughts I would write for any adapter: it makes sense up to a certain point. Yes, you can use lenses that are not available in native E-mount for now such as extreme telephoto lenses. Yes, you can use some unique lenses like the 18-35mm f/1.8 Art that only Sigma produces. I won’t deny there are advantages. But these lenses can also make the camera-lens combo much heavier and more unbalanced. a6300 + MC-11 + 150-600mm Contemporary

It has become compatible with the SIGMA 120-300mm F2.8 DG OS HSM | Sports for CANON EF mount, that has the latest firmware Ver.2.00. The converter feels quite solid and mounts very cleanly to the A7R MK1 test camera used for the review. The lens provided by Sigma for testing with the converter is the 24mm f/1.4 DG HSM Art which the adapter also mated to tightly. Aesthetically, the lens and converter matched fantastically. The new MOUNT CONVERTER MC-11 allows you to use your SIGMA SA-mount and SIGMA EOS-mount interchangeable lenses with the Sony E-mount camera body.In addition, since Sony E-mount camera bodies do not require mechanical integration with lenses for aperture control, the MOUNT CONVERTER MC-11 makes SIGMA interchangeable lenses for Canon cameras fully compatible with the automatic exposure control of Sony E-mount camera bodies. In addition, since Sony E-mount camera bodies do not require mechanical integration with lenses for aperture control, the MOUNT CONVERTER MC-11 makes SIGMA SA mount interchangeable lenses and SIGMA interchangeable lenses for Canon cameras fully compatible with the automatic exposure control of Sony E-mount camera bodies. Come the L-Mount Sigma provides the MC-21 electronic adapter which seem to work quite well with most Sigma EF mount lenses but is not particularly compatible with Canon EF mount lenses. Just one lens in particular - the very sharp and not uncommon Canon 135/2.0L would be interesting. Is it compatible as a bonus lens on the MC-11? To me the Canon EF 135/2.0 has been a bell-weather lens for an adapter compatibility. If the brand has mastered this lens then it has a good level of compatibility - if not it is really not seriously up to the job. Now just for fun, here are a few images made using the Sigma MC-11 mount converter with the Sigma 24mm f/1.4 DG HSM Art…

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 ContemporaryIt has become compatible with the SIGMA 24-70mm F2.8 DG OS HSM | Art for SIGMA, that has the latest firmware Ver.1.04. 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.