has no manual mode, then it would be quite helpful to use a tripod and the self-timer combination. in that case, the camera will be rock solid steady when it takes the picture.
if you have control of both the iris and shutter speed, and you have a powerful enough flash, then you can just set the shutter speed to something low...like 1/30 second or slower (like 1/15), and the iris to something wide, and then take a flash photo (without tripod) to see what results you get. if things are too dark, then your flash is probably not powerful enough. with flash photos in dark enough conditions and 'slow' shutter 