Photographers often think of low light situations as restricting their ability to take good photographs but nothing could be further from the truth. You see there are really two ways to view low light situations; you can seek to use them as a creative opportunity or see them as a restriction you need to overcome. Irrespective of how you personally view the situation there are lots of things you can do to ensure you can take great images in low light.
Low light means slow shutter speeds and you need to know how you will deal with this. If your shutter speed is too slow to hand hold you will end up taking blurred images (not always a bad thing). Ask yourself, do you want a blurred image or a sharp image? If you want a sharp image you need to find a way to support the camera so you can manage the slow shutter speed, or find a way to increase the shutter speed. We will look at some of the techniques you can use to achieve sharp images in low light shortly.
If however you want a blurred image then you may need to slow down the shutter speed even further so you can ensure the image is blurred and isn't just camera shake. Remember camera shake is poor technique and obvious. Deliberately blurring an image for creative effect requires good technique in order to appear attractive. If you want to experiment with creative blur in low light situations you should try to create shutter speeds of at least a second or more and experiment with different camera movements. Consider also experimenting with a shallow depth of field and defocusing the subject whilst moving the camera.
Low light conditions also provide opportunities for you to accentuate movement in your images, for example people moving around a train station or in a night club. It's often the contrast between sharp stationary objects and blurred moving objects that give such images appeal. Consider how you could use low light levels to create this contrasting effect. In some locations, the light levels might be too high for this, even when you reduce the aperture to its minimum. You can artificially limit light reaching your sensor to achieve longer shutter speeds with 8 and 10 stop filters, but don't forget you can also use a polarizing filter which will typically remove 3 stops of light.
Panning is another creative technique that can be used in low light conditions. Simply mount your camera on a tripod and pan the camera as you release the shutter. For the best results ensure you have the tripod level so that the horizon is level throughout the panning. I find longer lenses tend to give better results than wide angle. It's helpful to use a cable or remote release so that you don't need to press the shutter button as you pan.
If you want to create a sharp image in low light conditions, conventional wisdom says you should try for a shutter speed at least as fast as the focal length of your lens. For example, if you are using a 200mm lens then your shutter speed should be at least 1/200" or preferably faster. If your sensor is a cropped frame sensor and has a magnification factor then this will require an even faster shutter speed e.g. a 200mm lens on a 1.5x crop sensor effectively becomes a 300mm lens so needs a shutter speed of at least 1/300". There are however lots of ways to improve this to allow shooting at much slower shutter speeds.
The best and most obvious option is to mount the camera on a support such as a tripod but this isn't always possible. In such circumstances consider using other support such as a monopod, clamp or beanbag. The innovative gorillapod is very flexible and can be wrapped around railings and posts to provide a good support. The "reverse monopod" is also worth considering and you can make your own easily from a length of string. Attach a piece of string to the bottom of your camera (I tie it to a tripod quick release plate screwed to my camera) and tie a loop in the other end. Put your foot through the loop and bring the camera up to your eye so that the string pulls tight. You will need to experiment a little to get the length correct but once made it can easily fit in your pocket. This is an ideal accessory for inside churches and houses where tripods and monopods might be prohibited.
If you need to handhold your shots, good technique is vitally important. Where possible, try to find a position where you can brace yourself against something solid in order to reduce shake. Hold the camera too tight or away from you and you will introduce shake. I have a little Sony with an articulated screen which comes in useful for shooting at waist height. I find I can adopt a position with this camera at waist height that allows me to shoot as slow as 1/4s and still achieve sharp images. Brace the camera against something solid and you can achieve even slower shutter speeds. In this shot of the spiral stairs inside the London Monument the shutter speed was in excess of half a second and was achieved by holding the lens against the handrail.
When you come to take the picture be sure also not to snatch the shot but to carefully squeeze the shutter release. I would also suggest with slower shutter speeds to switch your camera onto continuous shooting rather than single shot (if your camera supports this). This allows you to keep the shutter button pressed and take perhaps 3-6 images in quick succession. I have found when I do this that usually at least one of the images comes out pin sharp despite the shutter speed being very slow.
Increasing the ISO is another obvious ways to achieve a faster shutter speed, the downside being increased noise levels. In recent years camera manufacturers have made great advances in high ISO quality and you can certainly achieve usable shots at ISO 800 or 1600. It's also worth considering the use you will put the image to and the resolution of your camera. If you have a 14Mpixel camera and you are shooting images for display on the web at 800-1200 pixels then you can get away with higher ISO than if you wanted to produce a large A3+ fine art print.
Do you shoot in RAW or JPG? When shooting in JPG your camera probably gives you little or no control over how noise is removed and you may find detail in your image becomes "mushy". Shooting in RAW will give you much more post production control over noise removal and allow you to fine tune this to your image, retaining far more detail.
Finally, if you have image stabilisation in your camera or lenses make use of it. I use mainly Canon equipment which has stabilisation built into the lenses. With my 70-300mm lens I find this gives around 3 extra stops and I can shoot quite happily at shutter speeds of 1/60" with a 300mm focal length. My 24-105mm lens also has stabilisation for which Canon claim 4 stops improvement.
Low light situations can offer some of the most beautiful and creative light but you need to have good technique to be ready to take advantage when the opportunities present themselves.