SLOphoto1: I just posted a video I made on You Tube about the problems the SX40 has in making nighttime time-lapse photos virtually impossible.
Solved with CHDK alpha version and scripts give you full control of ISO and extends shutter speeds http://chdk.wikia.com/wiki/SX40 . Soon there will be full version. CHDK does not violate warranty (as it is seperate soft run from card not from Canon SX40 internal memory ergo can not brick camera) Also CHDK enables RAW and much more fantastic options (e.g. Professional control - RAW files, bracketing, full manual control over exposure, zebra mode, live histogram, grids, etc. Motion detection - Trigger exposure in response to motion, fast enough to catch lightning. USB_Remote - Simple DIY remote allows you to control your camera remotely. Scripting - Control CHDK and camera features using ubasic and Lua scripts. Enables time lapse, motion detection, advanced bracketing, and much more. )