Let There Be Light
Filming outdoors at night is difficult not only because of the lack of light but also because of the sparse splattering of bright interference. You have quite a bit less control when outdoors and when you are in the absence of light you have almost nothing to work with. Here are a few tips for working outside at night.
The best way to use your camera is without a lot of reaching in terms of far images. What this means is that you are going to have more success if you attempt to use wide angle lenses and simply position the camera closer to the objects you are trying to capture. This is going to assist in depth of field as well as image clarity in the patchy vision of nigh light. Avoid zooming in too much as well because this rests on the same principle as the wide angle choice.
In the Manual
Only use manual settings on your camera for these situations. This is going to be true for almost all settings, mainly because you have to be very particular and the sharp light spots that occur against a dark landscape will throw auto-focus into a confused effort of back and forth focusing. You are going to have better luck doing things like focusing each image specifically to the unique situation. Though darkness looks as though it is one concrete element, the reality is that every outdoor night situation is slightly different in terms of light and saturation. That means the focus needs to be adjusted carefully each time.
Try dealing with light in a constructive way. You are going to need to use it because it is the basic unit for which the camera is looking, but it needs to be in your control. Try lighting small areas instead of attempting to capture the entire region. Then you can focus your filming on those patches, possibly even highlighting the partial nature of the light. Use gels to enhance or reduce the available light and shift the color balance. Go ahead and white balance like always, but make sure to do it in the correctly lit area where you will be filming. You can even try to play with this to alter the color of the night light by white balancing on slightly colored sheets of paper.
Always keep in mind that the night is not supposed to look like the day. The most natural images have mystery, do not allow you to see everything, and have certain amounts of distraction to them. That is the nature of the situation and being true to that allows for some of the limitations to be highlighted.