You'll find the settings in menu>shooting>optimize image>custom... play around with them + try different combinations to suit your pref's + shooting conditions (but you prolly knew where to find them).
The soft focus filter isn't part of the settings, it's a real filter (just in case you were busy searching for this fab-sounding setting on your D50
) if you haven't got one, get one, it's fab for softening skin tones.