This is a pretty general question, so you'll get a lot of different answers, but for
product shots, and the following critera:
extreme sharpness, low distortion, great contrast and a light weight (so you can
actually take shots without a tripod with no visible handshake - really speeds
things up,) and
on a budget - my vote today goes to the K 35 f/3.5, around
$90 - $175 depending on condition.
It's as sharp or sharper than the DA 35 2.8, and has pretty good close-focus
ability. It's a lens that doesn't get a ton of attention around here, but it should.
Crop:
Crop:
Another vote would be for the Vivitar 28 f/2.8 close focus ($50 - $80), but
good luck finding one that their owner is willing to part with.
.