I bought the 35mm 1.8 DX for portrait too on my 3100. Much better results than kit lens and it's cheap. But still not gd enuff ...faces look fatter for some reason. So I got the same question...should I get
- Nikon 50mm 1.4G ( wh gives me abt 85mm on FX scale)
- Nikon 85mm 1.4 ( gives me 135mm but angle seems too narrow)
- other brands like Sigma?
What is the best focus length on a DX for portraits ? I think tt my question
Looks like you found the same thing as I did when I had my D3100 (which is now with my wife).
For full length or 3/4 portraits, the 35/1.8G is a decent choice, with very little distortion. For half body shots, I found better results with the 50/1.4g stopped down to f1.8, while the 85/1.4D is an excellent choice for shots from shoulder up. There really isn't a 'best' focal length since it really depends on which of the above types of portrait you want to shoot. Bokeh is pretty much splendid across all three, esp (and obviously) if you put some distance between your subject and the background.
What comes into play is how close you get to your subject - the closer you get, while keeping background distance further, the better the bokeh, but get too close and you'll start seeing some distortion on your subject or fall within the MFD, and that's when you know you either need to compromise and step back, or get a lens with a longer focal length