Quote Originally Posted by neuroanatomist
Once you get above 60mm on the 15-85mm lens, you have an f/5.6 lens. For portraits, the desirable out-of-focus blur you want will, for lack of a better word, suck at f/5.6. You'll need f/2.8 (or less, which is why I mentioned the 85mm f/1.8!) to effectively isolate your subject from your background at these focal lengths.

Agree 100%.


If it's bokeh you want, you need a longer lens. The 15-85 is an outdoor lens and the 17-55 an indoor lens (doesn't mean it's bad outdoors); and this makes the 17-55 a more valuable lens.


It also seems you have conflicting requirements: wide angle and great bokeh. Most likely you'd need primes or a longer lens for that, but from what I've seen the 17-55 is the way to go.