One of my really good friends has been modeling for a good chunk of her life, and recently asked me to shoot her. On my end I have no experience shooting humans lol. I did a shoot with my 18-200VR but I'm wanting a more sharper lense. My typical shoot will be outside. Full body shots, half body, and some closeups. Im using a DX format camera, I dont plan on upgrading any time soon, maybe in 3-4 years when I get out of college lol. I was told to go look at the 24-70 or the 70-200, but i haven't seen much portrait samples from either lenses. What do you recommend?