hi, as this is my first time for a hair portrait shooting project at studio, i need you guys' suggestion. i owned nikon d7k & 50mm f1.8 (i forgot is 2.2 or 1.8), i came across that people is suggesting to use 24mm for this case at F8, then i searched there are 24mm f1.4 and f2.8, may need to rent, among these lens which one is most appropriate for my shooting as in sharpness wise too or other settings & equipments that u can suggest? thanks for help!!!