I owned the SX10 for the past year, the SX1 is the same but with the faster continuous and the HD vid.
The 1 second shutter speed is caused by the mode you're in, the same 15 second exposures can be obtained by using either the shutter priority mode or the full manual mode. Good luck
I thought the SX1 was the same as the SX10, but with less camera ability and more video ability. I can only get a 15 second shutter speed in the special "Long Shutter" mode. I have both the camera and manual with me right now and in both "shutter priority mode" and "full manual mode" the shutter scale will only let me go to 1 second. Anything higher doesn't even show up on the scale to begin with.
I've been looking through the manual for a while and the only time I've been able to find anything on a 15 second speed is in that "Long shutter" setting. To me at least, that setting seems kind of useless since you can't change anything else, like aperture or the iso properties, in that mode.
Maybe I'm missing some kind of special button somewhere that'll allow for the extra 15 seconds in "shutter priority mode" or "full manual mode," which knowing me could easily be the case. haha I guess it'll just come down to whether I'd want the more customizable 15 seconds or HD video then. I'm kind of leaning toward the SX20 though.