is it just portraits? Is it environmental 'gyus at work' stuff? If you;re doing portraits, I'd personally use an 85mm, or a 105mm or somehting longer than a 50mm.
I say this because with a 50, and if you want to fill the frame you'll be about 2 steps away from the subject which is a little bit too close for comfort unless you are on good terms with the person. With a longer lens there is no worries, and also less distortion (yes, even 50mm lenses distort).
My vote goes with a longer lens. A 24-70 is a nice general purpose thing to have to cover eventualities, but to me it isn't long enough for portraits, and doesn't really provide decent working distance between me and the subjects. I don't mind getting close, but some subjects might be a little weirded out by standing in their 'bubble' with a camera.
Now, if you can find a 70-200 you'd be sorted! |