I'm an SLR newbie shooting with a D80 and a Sigma 28-70mm f/2.8 lens. My shots are not always crystal clear. Sometimes they are but rarely. At 100% full rez. (10.2mp), my images are about 95% sharp and slightly "soft". They have a faintly blurred halo especially around the highlights. I'm usually shooting at 100 ISO, 2.8 - 3.2 Aperture Priority.
Also, I use an SB600 and I usually bounce it straight up with an index card rubber banded and the diffuser in place.
What might I be doing wrong?