Brian
You'll need to experiment to find the optimum settings for your camera lens aperture/ISO/exposure time combination.
I've done quite a few shots with my Panasonic LX5, many turned out quite well. This compact however is a fairly unusual compact:
- can do exposures up to 4 minutes, most compacts stop after 30 sec or less;
- full manual control of all settings;
- you need a fast lens - the LX5 lens is f2 and sharp to the corners. Cheap compacts with f/4 or f/5.6 lenses simply won't record much more than a few stars.
In practice I found exposures for 1 minute at ISO400, f/2 were optimal. While you could increase ISO all this did was increase the sensor noise (background speckle) without really capturing more stars/nebulae, while reducing the exposure time didn't fix this.
It worked even better if I set it to ISO 80 on a tracking mount for 4 minute exposures, but you need a mount that tracks the sky for that. Without that you'll be limited to a minute or so before the earths rotation produces star trails.
Another aspect concerns vibration. Even though I sometimes put the camera in a rock (leave the tripod at home, IMHO they're not much help) the trick here is to use the self timer (assuming the camera has one) so the camera will settle before the shutter opens a few seconds after you take your mitts off it.
Lastly don't panic if there's a long pause after a shot taken with a long exposure - the LX5 and many others all do dark-frame subtraction in the camera. What this means is that it takes a black shot internally of the same duration and subtracts this from the real shot, in order to remove some of the sensor noise.
|