I haven't tried replacing the batteries yet. The camera says they batteries are still full with poer but I guess it could be wrong. I look up the shutter speed on the internet and for my camera it says
Shutter: Electronically controlled vertical-travel, focal-plane shutter
Shutter Speeds: Automatically set between 30 seconds and 1/2000 sec. in Auto mode, VariProgram modes, P and A; in S and M: 30 seconds to 1/2000 sec. (in 1/2 EV steps); Time provided.
When I took these pictures I used the auto mode. That is what I usually use.