Many people describe that photographing at night can be both challenging and rewarding. This is very true. Photographing at night can be one of the most dramatic situations that you can photograph under. Photographing at night provides very special challenges to observe and correct. If we describe photography as literally “painting with light” then we immediately understand the special challenge of photographing at night. There isn’t much paint.
This doesn’t mean photographing at night is impossible, it simply means that we need to think about things a little bit differently. Photographic cameras are meant to typically deal with light on the planet earth. 95% of time this means dealing with light during the daytime. The aperture sizes, shutter speeds, and film or sensor sensitivities are all conceived to deal with daytime on planet earth. They are flexible enough to deal with nearly all types of lighting situations, but beyond the realm of daytime, things start to become a bit more complicated.
You need a tripod. There is no way around this, unless you have a special talent for holding perfectly still for dozens of seconds to minutes at a time. Shooting photographs of the sky presents a couple of difficult challenges. First is that you need to make long exposures. When you shoot long exposures with a digital SLR, there tends to be a more extreme accumulation of noise then is typically seen in shorter exposures. This is why many cameras feature a long exposure noise reduction feature. This is also why digital sensors that are fixed in massive telescopes throughout the world are fitted with their own cooling systems. The cooler a sensor is, typically the less noise there will be.
So the real trick is balancing your aperture size, shutter speed, and sensitivity to allow enough light in, without gaining the nasty bits that you don’t want to see in a photograph. It would be easy to set your sensitivity to 3200 and shoot exposures that are a few dozen seconds in duration, but the resulting image would be so grainy and so full of noise that it would not be practical, unless this is the effect you are going for. Likewise you could use a bulb exposure to take a 2-hour exposure, but you would get star trails, and probably a very grainy image due to the long exposure.
The best thing to do is to give it a try. Try out various focal lengths, sensitivities, aperture values, and shutter speeds. See what works, and what the various effects of the different settings are. Either way, it’s easy to get captivated by being able to see the heavens only the way a camera can!