IMHO, some of the advice given is misleading for a person being at the beginning of the leanring curve. So, let's try to clarify a few things ...
Originally posted by timstone I tried bringing up the exposure in the raw program I use but it made a crazy amount of noise appear. I used ISO 800...not really sure why.
You may first want to understand three things or so ...
1. bringing up the exposure in raw by one EV (one stop) and doubling the ISO at the time the exposure was taken (aperture and exposure time being constant) is almost exactly the same. 4 stops (the max. in LR) and your ISO 800 becomes ISO 12800.
2. Reducing the image size by 50% (25% #pixels) is like halfing the ISO setting. Which is why the noise in your web sized images is invisible.
3. Use the highest possible exposure time and ISO setting without overexposing, with priority on exposure time.
4. You can take multiple images and stack them. Stacking N images reduces ISO to 1/N. This allows for night photography w/o a tripod.
Originally posted by Ash I would emphasise the suggestion to use low ISO (100 if possible) for any exposures greater than a couple of seconds - the longer, the more need to keep ISO low.
I claim the opposite. Use the highest ISO w/o overexposing. With the K-x, it doesn't matter much either way though.
But of course, capture as much light as possible, i.e., use longest possible exposure time and largest aperture.
Stacking can be a great means to deal with the high dynamic range you find in many night scenes.