Low light and night time photography can be a bit tricky unless your familiar with a few basics about photography in general and the differences between normal day time photography and night.
The bad news is that your only likely to get great results by using manual mode on the camera where you set the shutter speed and aperture yourself. The good news is that night photography is much more forgiving than daytime when it comes to exposure, a fraction of a second makes a big difference to exposure during the day but at night you can err on either side by anything upwards of three or four seconds without spoiling the shot. I try and use a constant aperture of F5.6 and work the shutter speed around that.
If your using a secondary source of light, a flash or torch, the impact this light source has is generally controlled by the aperture first, the exposure of sky and landscape beyond is controlled by shutter speed. By setting the aperture at 5.6 I know pretty much automatically how much flash I need to use to get the high contrast I want without large bleached out white bits. This comes with a bit of experimenting and error.
The shutter speed then is dependent on whether there's a full moon, clouds or street lights. On a very dark night with no moon or street lights your looking at an exposure of 3-4 minutes as a starting point, the same amount of flash is used irrespective of the length of exposure. For the hour after sunset, shutter speed is usually between 30 seconds to one minute @ ISO 100.
There are a few other issues you need to be aware of when taking photos at night, firstly the extent of star trails depends on the focal length of the lens and the exposure time. The wider the lens, the longer the exposure time you can get away with with no star trails, if your using a long zoom lens then your exposure time has to be much shorter before trails appear. Because of this, a super wide angle like my Nikkor 12-24mm or Tamron 11-18mm is perfect for shots of star filled skies with the landscape below, you can get away with much longer times because of the short focal length, giving nice pinpoint stars. There are complicated formuls for predicting the exact length of star trails for a given focal length and exposure time but at wide angles, you can generally get away with 30-40 seconds with small star trails.
One pitfall that is easy to fall into is night photos coming out like underexposed, desturated daytime pictures, especially under a full moon. Film photographers generally used tungsten balanced film to preserve the blue glow of night and you can simulate this with a digicam by selecting tungsten white balance (though most cameras still turn out overly blue photos). You may need to tweak this a bit later.
The reason for the above is nothing to do with the camera or the film, its our eyes. Our retina is made up of two different type of 'sensors', rods and cones. You have a lot more rods than cones and they are much more sensitive to light, unfortunately they only really come into play in the dark and they dont 'see' in colour, only shades of grey. What that means for a photographer is that the photos come out much more colourful than you would remember, nightime really is that colourful, we just cant see it with the naked eye. You can desturate if you want in photoshop, I generally tone down more now than I used too because people assumed I had pumped up the colour in photoshop, not knowing there eyes naturally tone down the colour at night! How ironic that these are sometimes derided as faked/false!
With digital cameras you can now up the ISO (sensitivity) of the sensor on demand and lots of people crank this all the way up for night photography. If you are using a tripod already (and you should be!) then there is no reason to turn the ISO up, keep it down as low as possible and definitely no higher than 400. Only go this high if you are doing so to avoid star trails by using a shorter shutter speed than you normally would (or your using a penlight to illuminate the stones!). Turning up the ISO gives nasty grain and amp noise, amp noise is produced as the sensor heats up during its longer period charged up over long exposures. It shows up as bright ("hot") pixels where there should be none (can lead to whole new 'constellations' being discovered when you get home!) and also as purplish/greenish blooming around the edges of the frame. Some cameras have a 'dark frame subtraction' noise reducing mode for long exposures, if you have it you might as well use it. The downside is that the camera takes a second picture after your exposure is finished, only this time with the shutter closed so it can pick out which pixels are overheating and cancel this out. These second exposures can take as long as the first exposure so for a three minute exposure you could be waiting 6 minutes before you get to see the result, by which time the moon has moved changing your composition....
The best time to photograph the moon and include the landscape is when it rises shortly before or after sunset and is almost, but not exactly, full. At this time you can get some detail in the moon and still have some blue on the sky, when the moon is just less than full you also get some shadow (and hence a touch of depth) which makes it look more realistic. If you want a large moon above a specific landmark then you will need to move a long way back from the subject and use the longest lens you have and try to frame it while the moon is still low. Can be difficult, but not impossible and makes a great picture!
Dont forget to pack extra batteries for your hand torch in case you use them all up lighting up the stones like I did once or twice! Wear one layer more than you think you need, standing still for a long time makes the cold bite a lot harder, bring a good set of gloves as well because cameras are next to impossible to operate with frozen fingers and dont forget some treats and a flask!
Happy snapping!
