The A series is viable for Murph as he stated he wanted to use his rechargeables and they really are not that big. I agree that the batteries for the SD series are great. I have the extra battery and charger and I have never been with out the camera in working condition. Those batteries seem to last about 1000 pics, exaggerating a little here, as I never take quite that many at any one time but over a few months we take 100-300 and I swap out the battery 'just in case'. I thnk I have only run out of battery once and the spare one was charged and ready to go.
