Using Canon EF Lenses on Sony A7-II with the Commlite CM-EF-NEX and the Sigma MC-11 Adapters

The main reason for me to buy the Sony A7-II was the possibility to use some perfectly good and sharp Canon EF lenses I already have by using an EF to Sony -E electronic adapter.

There are many brands and models of adapters, from Sigma, Commlite, etc. I choose the simplest one, the Commlite CM-EF-NEX to evaluate the possibility first.

Commlite CM-EF-NEX
front view

Commlite CM-EF-NEX
back view

The adapter is all-metal made and very sturdy. It has a removable tripod mount.

The lenses I tested:

Canon EF 40mm F2.8 STM

Canon EF 50mm F1.8 STM

Canon EF 24-70mm F2.8 L

Canon EF 24-105mm F4 L

All four lenses above worked very well with the adapter on the Sony A7-II with a fast and precise focus.

Canon EF 24-105mm F3.5-4.5 STM

This lens was very unreliable with this adapter. Strange things happened like long minimum focus distance at the wide-angle setting and erratic autofocus at all focal distances. 
The problems are more common at the wide-angle setting. My lens can't lock the focus at 24mm, but works well from 35mm and up.
This lens is listed as compatible on Commlite's website.

Canon EF 50mm F2.5 Compact Macro

Sigma 70mm F2.8 EX DC Macro

Both lenses worked but with slow focus and lots of hunting.

Canon EF 17-40 F4 L

Canon EF 24-85 F3.5-4.5 USM

Both lenses worked ok. Not fast but very usable.
Lots of hunting on the A7R but ok on the A7-II

I also tested the 17-40 L and the 40 STM on the A7R (first version). They worked but very slow.

The Sigma MC-11 worked perfectly with the Canon EF 24-105mm F3.5-4.5 STM and the Sony A7-II, so it's obvious that the problem with the Commlite CM-EF-NEX is due to some kind of firmware limitation. The MC-11 is much more expensive but it's also much better.

The choice will depend on what lenses you have.