[toni-a]

Yesterday I used my helios 58f2 for portraiture for  its swirly bokeh, I used it on Sony A6000 and on Canon 5D classic to capture portraits for my wife and daughter.
On A6000,  I got 70% of shots is sharp focus, (when focus is on the farther not closer eye, I consider it misfocused) note the  the model wasn't  standing still, she wasn't walking or running nonetheless.
Using autofocus I have almost the same  rate of sharp focus especially when using 7Dmkii along with 85mm f1.8 , 55-210 on A6000 has a large DOF so can't compare it.
What would you prefer to use for portaiture AF or MF, just to discuss habits, I am not expecting a clear cut answer

[stoppingdown]

I can't directly comment on the AF/MF thing, but I'd like to point you out that the 58f2, at full aperture (which I suppose you're using for the swirly bokeh), is sharp only in the center of the image. You can check it looking at the two lighthouse pictures posted here:

http://stoppingdown.net/blog/the-zenit-helios-58mm-for-flower-macro-photography/

So, if you want to have a certain degree of sharpness of your subject, you should take care in composition, by keeping it near the center of the frame (if you don't like the composition, you can crop it later). I suppose that if you want swirly bokeh, it's natural to think of center-based compositions.

You might want to run a few tests yourself, because the behaviour at shorter focal distance might be different.

Also be aware that on an APS-C camera a good deal of the swirly bokeh is clipped out.

[thxbb12]

AF a million times.
Since almost all of my family portraits are candids, I heavily rely on AF.
MF would be very challenging and mostly OOF most of the time.

[obican]

Whatever is available.

If the camera has good Eye-AF (like my A7 with native lenses), I'll surely use that. However, it's never foolproof and sometimes fails to detect the face and the eye. In those cases, my camera is set up in a way that unless I manually press the Eye-AF button, it's in the smallest spot focus point available so I just use that and recompose. This is also what I use if the lens is not native and Eye-AF is therefore not available.

I also don't mind manual focus lenses. The trick with mirrorless is not to rely on focus peaking as it's hugely misleading, especially on FF sensors. I simply magnify the focus area and focus that way, it's just as quick and much more reliable in accuracy.

If none of that is available (like my Hasselblad 500C/M or Rollei), I'll just slow down and direct the subject in a way they don't change the distance between the camera and themselves. Also, stopping down a bit doesn't hurt anything as long as you don't obsess with infinitely blurred backgrounds (I don't).

[toni-a]

I can't directly comment on the AF/MF thing, but I'd like to point you out that the 58f2, at full aperture (which I suppose you're using for the swirly bokeh), is sharp only in the center of the image. You can check it looking at the two lighthouse pictures posted here:

http://stoppingdown.net/blog/the-zenit-helios-58mm-for-flower-macro-photography/

So, if you want to have a certain degree of sharpness of your subject, you should take care in composition, by keeping it near the center of the frame (if you don't like the composition, you can crop it later). I suppose that if you want swirly bokeh, it's natural to think of center-based compositions.

You might want to run a few tests yourself, because the behaviour at shorter focal distance might be different.

Also be aware that on an APS-C camera a good deal of the swirly bokeh is clipped out.

Obviously I would be using this lens just for the swirly bokeh since I have many alternatives to it when I want border sharpness or just sharpness, so I am doing just what you suggested, as for full frame vs APS-C I didn't notice any big difference, it is doing just fine on my A6000