Does Sony A7 IV work with Canon EF 70-200mm f/2.8L IS III via Sigma MC-11?

What works & limitations

• Physical mount: Sigma MC-11 bayonet-locks to the Canon EF mount on the lens and Sony E-mount on the camera — no play or wobble when properly seated; the MC-11 adds 29.8mm to the flange distance
• Phase-detect AF functions in single-shot (AF-S) mode — acquisition time is approximately 0.25–0.35 seconds at 200mm f/2.8 for static subjects at 3–8m, reliable for portraits and product photography
• Aperture control via MC-11 electronic pass-through — full range from f/2.8 to f/32 commandable from the A7 IV body; the aperture responds to the command dial in real time
• EXIF focal length (70–200mm) and aperture (f/2.8–f/32) transmitted correctly through the MC-11 — Lightroom and Capture One read the focal length accurately for blur correction and lens profile matching
• Canon IS III operates during shooting — the A7 IV detects IS presence and reduces its own IBIS pitch/yaw correction to avoid IS/IBIS conflict at shutter speeds below 1/200s
• Manual focus with the A7 IV's focus peaking display (Peaking Level: Mid, Peaking Color: Red) provides clear manual focus confirmation at 200mm f/2.8
• Real-time Eye AF and Animal AF are unreliable or non-functional with the Canon EF lens via MC-11 — Sony's subject recognition AF uses lens-specific communication not available through third-party adapters; face detection works intermittently but Eye AF does not engage reliably
• Continuous tracking for fast subjects — BIF (birds in flight), motorsports — is significantly degraded; expect 30–50% keepers at 10fps burst versus 80–90% with native Sony GM lenses in equivalent conditions
• Some Canon IS modes may not communicate correctly with A7 IV — IS Mode 2 (panning stabilization) can cause erratic IBIS interaction at 200mm, visible as wobble in the electronic viewfinder during panning shots
• Sigma MC-11 firmware version 1.15 (released 2022) improved AF compatibility with Sony A7 IV specifically — update via the Sigma USB Dock (UD-01); without this update, AF acquisition speed at 200mm is notably worse and intermittent contact errors occur on first mount
• Sigma MC-11 is the most compatible EF-to-E adapter for Sony A7-series bodies based on community testing; Commlite COMet and Viltrox EF-E5 adapters have documented intermittent AF loss issues specifically with the Canon 70-200mm f/2.8L IS III due to IS motor current draw during startup
• The Canon EF 70-200mm f/2.8L IS III weighs 1480g; combined with the MC-11 (205g) and A7 IV (658g), the total handheld system is approximately 2343g — a tripod collar on the lens (included) is essential for handheld use above 30 minutes; use the rotating collar to balance the system on a monopod
• For users wanting native Sony performance at 70-200mm f/2.8: Sony FE 70-200mm f/2.8 GM OSS II (SEL70200GM2) is the direct alternative at approximately $2,800 — it is 30% lighter than the Canon+adapter combination and fully unlocks the A7 IV's Eye AF, Animal AF, and 10fps burst tracking