AF woes with Commlite EF-NEX adapter on A7R III

As sort of continuation to my camera upgrade ponderings, the other day I spotted a second hand copy of Canon version of Sigma 150 mm F2.8 Macro for sale and decided to bite the bullet and investigate if that could be solution to move forward to switching solely to E mount ILCs.

I had readily Commlite EF-NEX adapter that I already got some years ago and haven't really used so far since I haven't had EF lenses. I first tested this adapter and my "new" lens on α7R IV and that seemed to work pretty well, but now I switched to α7R III and that combination does seem to struggle to autofocus properly (even more than my A mount version of this lens and LA-EA3).

I guess that there might not be anybody with exactly this lens, adapter and camera combination in Dyxumers, but does anybody else use that adapter or any other EF-E adapters? Especially on α7R III. I did check the compability lists for Sigma MC-11 and Metabones Smart Adapter and I only the latter mention this Sigma 150 mm macro as compatible lens. Of course, the easy solution could be solely use this lens and adapter combo on α7R IV, but most of the time I want to hook that camera to FE 200-600 G and keep the older camera for the shorter lenses and uses that do not require the faster AF. Or at least as long as I don't own α1, α9 [II] or another α7R IV[A].

Does your adapter have the latest firmware?
When you say struggle, what do you mean?

I found two reviews of the Sigma 150mm on Sony A7 cameras:
Mirrorlessons.com with the Metabones adapter on the A7r2 and describes AF as "not reliable".
Phillipreeve.net with the MC-11 on the A7r2 and describes the AF on the adapter as a weakness.

It might be the lens that is less suited for AF.

addy landzaat wrote: Does your adapter have the latest firmware?

Unfortunately this adapter does not support firmware updates. I think this is already quite old model, especially as the model name includes NEX and it defaults APS-C mode (probably because it fakes its identity as "LA-EA1"). The story behind buying the adapter is that I wanted an EF-E-adapter in case I would borrow Canon lenses from some birding friends, but so far that has not happened. And since I was unsure about how much I would need the adapter I was cheapskate and chose this one instead of the more expensive options...

addy landzaat wrote: When you say struggle, what do you mean?

AF hunts very much and most of the time seems to fail to lock on anything.

addy landzaat wrote: I found two reviews of the Sigma 150mm on Sony A7 cameras: Mirrorlessons.com with the Metabones adapter on the A7r2 and describes AF as "not reliable". Phillipreeve.net with the MC-11 on the A7r2 and describes the AF on the adapter as a weakness. It might be the lens that is less suited for AF.

AF works fine when I use this lens and adapter with α7R IV, so I think the lens is the least likely culprit causing the trouble.

I can't answer your question specifically , only tell you my experience with the commlite ef-e adapter .
The first one I bought was not long after I got an NEX 7 about 8 or so years ago .
It was a poor effort for focus and probably got chucked in a draw never to be seen again !
Skip forward 4 or 5 years .
Having got some more quite good Canon lenses I thought I'd try again and got another ( later version ) , and AF was much improved .
Indeed it wasn't much slower than the NEX 7 !
Skip forward again to last year .
I had ordered up an a7iii at a local shop and was calling in to try some lenses on it before deciding on whether to buy or not , just as Sony announced the LA-EA5 and said it wouldn't work on the a7iii , so that stopped me buying that camera !
I did call in as I was buying a lens off them anyway , and tried the Commlite adapter on it , and the camera just came up blank staying something like incompatible lens / or accessory .
It didn't matter what lens was on it , still nothing .

Move forward to a few weeks ago , I've bought a used a7Riv and the Commlite works just fine with it .
No PDAF , just contrast , but I thought that would be the case .
But it worked as intended regardless .

I've now bought the MC-11 and it's much better .
With all my Canon and Sigma EF lenses I've tried on it so far , it also works fine .
PDAF , eye AF etc .
It only works correctly in single shot AF , not continuous AF or auto .
In either of those two settings it greatly front focusses and image stabilization seems to be also off.
However , sigma does state anything other than single shot AF requires a compatible lens , so only new Sigma lenses if a certain range .