This exercise is reminiscent of an exercise from the Art of Photography course, experimenting with focal length; here though we are to investigate the effects on a portrait.
Wide angle lenses (shorter focal lengths) distort the perspective of a subject and can be of great use to inanimate objects, and especially good for landscapes with sweeping skies giving the image a greater depth of feel and awareness as if we were almost there. This effect of perspective change on portraits, or faces in particular, will look a little unnatural and therefore I am expecting close up shots with a wide angle lens not to be at all flattering. Faces may appear 'fatter' and facial features stretched with extreme differences in focal length.
For this exercise I took several images with the same lens at both ends of the zoom (24mm-70mm) trying to keep the same framing. All ISO and aperture settings remained constant at iso 100 and f/3.2.
Below are the best two examples, the first of which is at 24mm, here the width of the face has been changed and the mouth elongated with quite broad cheeks and the nose looks bigger. As an image it almost look 'too hard'.
The second version taken with the same framing is at 70mm and shows a much more natural perspective, that is much softer. This leave me to wonder if a wide angle lens could be creatively used in a portrait to give a more menacing portrait of a man? One to investigate.
In summary it is quote obvious that a more flattering image can be taken at longer focal lengths. As the standard lens is 50mm or 35mm on my camera crop, I am guessing that this would be the minimum focal length to use. I do have a lens with longer lengths and have taken great portraits with this in the past, getting really close without prying into the subjects space, as these have worked well I am guessing that there is no or little limit to using focal lengths beyond 100mm. I will have to break out the bigger lens for other images.