
Originally Posted by
Baker
The lens that gives me the closest focal length to 24-70 on my T2i would be the 17-55mm f/2.8 which is the FF equivalent of 27.2-88mm.
Closest focal length, yes. But in terms of depth of field (often quite important for portraits), the FF equivalent of the 17-55mm f/2.8 is actually 27-88mm
f/4.5 (which means than when used on a FF camera, a 24-105mm f/4L is wider, longer, and can provide shallower DoF than the 17-55mm when used on a crop body. You'd need a nonexistent lens - a 15-44mm f/1.75 - to profide equivalent framing and DoF on a crop body to the 24-70mm on FF. If you want thin DoF on crop, within a reasonable budget, Brant's suggestion of primes is the way to go - lenses like the 85/1,8 which you have, and a 50/1.4 for looser framing.