[font color=\'#000000\']intrav, my experience with the Canon- and other-brand BP-511s and -12s in D30s and '60s has been inconsistent, but if you're getting only 20 to 30 shots before the battery is down to indicated-1/3 capacity, there's something wrong with your batteries or charger or charging techniques. Do you leave the batteries on the charger an hour or 2 after the light is on solidly? I leave mine on overnite sometimes and they seem to last longer. I'm using Battery Barn's 1500mAh BP-511/12s (only $44 delivered) and they last longer than Canon's 1100mAh versions and the one Lenmar 1200 that I have.
I've seen the belt-carried high-capacity batteries recommended for the '30s and '60s but wasn't interested and don't remember the brand name. I'm sure you can find one using Google or another search engine.[/font]