I really think we should be careful with taking for granted what
only one user has reported so far. If his autofocus is really broken, I´m fully convinced it´s a coincidence and has nothing to do with using MFA on other than Sony / Minolta lenses. Moreover, if it were true, I´m sure Sony would issue the much awaited FW update or recall the cameras: think about it, all they warn against is using third party lenses which
may cause disfunctioning of brand dedicated lenses. Next conclusion should then be that it will be fine using third party lenses only, as there´s no warning against that, driving people having the flaw away from purchasing SALs and stick to 3d party...
Now, how intelligent can hardware be, discovering some lens is a genuine Sony / Minolta hence punish according to the book, because also remembering a Sigma has been mounted before?
It really does not make sense to me; the conflicting IDs story however gives a logical explanation which suits me fine. Or to quote Spock, when all has been explored, the only remaining valid explanation, however unbelievable, must be the truth. Here, I think it´s not even unbelievable. I will of course not buy a Sigma 120-400 because of it, if that were the only difference with other similar lenses, as it´s likely to conflict with my Sigma 50.
Besides, over the last two days, needing to carry light, I had the Minolta 35-105/f3.5-4.5 with me instead of the usual trio. It behaved fine (on AF that is), in line with the above, as it´s not conflicting with anything afaik (ID 2554). I´m fully confident the 70-400G coming soon will do just as fine, as its type ID 53 is not conflicting with anything else either. I´ll let you know when I do. Also note that DxO has a lens module for the Sigma 12-24 for all alphas except the 300.
I wonder though what happens to people having and using both AF DT 18-70mm F3.5-5.6 and AF DT 18-200mm F3.5-6.3. Those have conflicting IDs as well, 40 for the 18-70, 40.1 for the 18-200...
In conclusion, while his problem might be real, I think Roy´s analysis of it is plain wrong and really a non issue...