- leave it at the same aperture at which you are shooting (i.e. if you’re shooting at f/2 or f/2.8, then set the DC ring at f/2, or f/2.8 in either direction) to get beautiful bokeh and a sharp subject; in this case, your bokeh will be more pronounced either behind or in front of your subject (assuming there are things in front of the subject which are out of the depth of field or focal subject). An example: a row of flowers in a garden in front of the subject, with focus on the subject set, and shooting aperture of f/2.8 = setting the DC at f/2.8 “F” (“front”) causes the flowers in front of the subject to have ‘more bokeh’ than normal, whereas setting it at “R” (“rear”) causes the same for the rear row of flowers (although this is a bit harder to see unless you’re at narrower apertures where you usually don’t get that much creamy bokeh).

- set it beyond or below the aperture you are shooting, to gradually ‘defocus’ the subject that is already in focus. Now this sounds like anathema to anyone who wants “sharp” photos from lenses (as “sharpness” is one of the big selling points) but for portraits specifically, a tack-sharp shot is in fact not always what you might want. For older, more ‘mature’ subjects which may have the various blemishes, wrinkles, lines, etc. which would be very pronounced and distinct in a tack-sharp lens’ focus, a slight change of the DC (‘defocus control’) ring allows for th