I have all of my cameras set to 105mm. I noticed that the head of my figures were elongated and asked about it and was told to use a setting of at least 105mm.  I've never tried anything higher as this seems to work fine for my needs.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi