I don’t often use my 25 YO Minolta 70-210 f4.0 zoom but this old ‘Beercan’, especially at portraiture focal lengths, is very sharp and has creamy Bokeh.
I personally never shoot a head shot at wider than f4.0 if I can help it because DOF becomes just too thin.
This is a 100% crop of the original that was shot wide open and horizontally (6000 pixels wide) for project purposes. By 5.6 the lens maximizes sharpness.