Whether you are shooting indoors or out, low light photography can be both beautiful and challenging. Not metering on the right spot in the scene can cause an image with blown highlights, clipped shadows, and unwanted noise. With the shutter too slow, there may be camera shake or blurred subjects. Finding the best solution is about knowing your light and equipment. Let's explore these areas now.
Chasing the Light
Knowing the light of your scene is perhaps the most important step. At dawn and dusk, the light goes through several phases and color changes due to its interaction with the atmosphere, smog, pollution, and so on. Knowing the times of these changes can help you better prepare for your scenario.
The blue hour (which is actually about a half hour, depending on location and time of year) occurs when the sun is below the horizon (-4° to -8°), either just before sunrise or just after sunset. Also known as civil twilight, diffused sunlight is indirectly visible as it bounces off the atmosphere creating a cool blue glow. In the evening, interior and street lights flicker on and make for wonderful architectural and urban work.
As the sun nears the horizon, it quickly changes to the golden hour. Still diffused, the atmospheric colors move from the cool blues into the warm reds, oranges, and yellows and is an excellent time for portrait and landscape work. The sky bathes everything in soft warm light and gives your subject a dreamy glow. At sunrise, the golden hour continues from -4° (end of the blue hour) until the sun is about 10° above the horizon, and at sunset, from 10° until it crosses just below the horizon at -4°. The golden hour, on average, lasts about 50 minutes where I live.
The morning golden hour gives way to daylight while the evening blue hour, through increasingly deep hues of blues and purples, gives way to night. Depending on cloud cover, daylight progresses with increasing contrast and less diffused light in your scene.
Knowing the range of colors, amount of diffused light, and how contrasty the scene will be ahead of time gives you full control of how your final image will look. The next step is having the right gear for the right light.
Low Light Gear
Any camera body can shoot in low light. The speed of the glass and the sensitivity of the sensor or film will dictate just how much light the camera will capture. Modern digital cameras have become fantastic at low light, allowing higher and higher ISO speeds without introducing much noise. Knowing how well your camera handles high ISO is important to know as there is a tradeoff between shutter speeds and acceptable noise.
Fast glass is also important. The faster the glass, the lower the ISO you need, and the less noise the digital sensor will introduce. This also is important when shooting film, knowing the limitations of pushing your chosen stock. I'll comfortably push most of my stocks two stops without worry. I am a big fan of fast glass and like to have something between f/1.2 and f/2 for shooting in low light conditions.
As the shutter speeds slow, the chance of camera shake increases. I always recommend a good sturdy tripod when shooting in low light, especially when the sun dips from civil to nautical twilight. Different people have different speeds they can safely handhold a camera. If you think there's even a chance you will shoot slower than that, have a tripod.
A good light meter is also a great tool shooting in low light. The conditions change so quick during the twilight hours that, unless you've been doing it a long time, you can miscalculate your settings. Though modern digital cameras have good built-in meters, I much prefer a dedicated external spot meter.
Shooting in Low Light
With the right gear and an understanding of the light you'll be shooting in, here are the basics I go by.
1. Shoot Open or Close to It
Take advantage of the speed of your glass. Those extra couple of stops in extremely low light can save you from motion blur or the introduction of digital noise. With subjects off in the distance, I do not worry about the depth of field and go as fast as possible. With a close up subject, I may need to stop down a couple stops to give me the proper depth of field.
2. Raise the ISO to Where You Are Comfortable
Though modern cameras can go extremely high, I try not to go above ISO 3200. And it's rare that I actually go that high. If you exceed your limits of a clean file at higher ISO's, use software to reduce this noise. Major photography software vendors have some excellent tools for doing so.
3. Shoot Manual
Don't rely on the camera to work out your settings in low light. They are getting better at it, but they haven't matched human ability here. So know how to use your camera in M mode. Short of that, shutter priority will do. But for crying out loud, no P mode. I suggest pulling out your handy meter to find the best combination of ISO, shutter, and aperture for your scene and transfer the settings to your camera.
I tend to have a desired shutter speed for a given scene (based on hand-held or tripod) and know I want the aperture fairly wide open. From there, the meter will give you the best ISO to capture the light. I am comfortable shooting a 50mm at 1/30 handheld. Leaning against a wall or bracing my elbow on my knee, I may go down to 1/15. But anything slower I am either boosting the ISO or going on a tripod. Again, know your limits.
4. Properly Meter the Scene
Chances are you'll have mixed light in the scene; either with a splash of bright light (a bright cloud, street lights, mountain tops licked with sunlight, and so on) or some pitch-black shadows. I am OK with some clipped shadows in a dark scene. So, I meter for the highlights to ensure they are not blown and I can usually recover the necessary shadows to tell the story. It's easiest to meter these lights with a spot, but I have also used my cameras histogram in a pinch, making sure there's no clipping of the highlights.
5. Use Long Exposure from a Tripod
If the scene allows use of long exposure, be sure to be on a tripod. If the camera has the ability, turn on the long exposure noise reduction capability.
6. Frame the Highlights Within the Scene
This is a personal objective of mine in low light photography; especially when shooting urban or landscape. In the style I shoot, the highlights of a dark scene play a huge role in my framing of the shot and are often as important as the main subject. While framing the scene, I first look at how the subject, be it a mountain or a building, sits in the finder. Then I evaluate the lights and how they balance out the scene. These lights can be the porch lights of a hotel or a mountain peak grabbing the morning's first light. I evaluate both aspects of the frame and find the best balance that suits them.
The tips I gave above are a general guideline I go by, and are in no way hard and fast rules of photography. There are times when you may want to take advantage of creative blur or purposely under or overexpose an image. Playing with the light is half the fun in photography!