At the most basic level, all pictures are just light interacting with chemicals. Photography requires light in almost every situation, so the more light you have the better off you'll be. Unfortunately, there are plenty of situations in which photographers do not have the benefit of added light, and thus are forced to think on the fly. Here are some tips for how you can use your camera without a flash to get great results in low light environments.
Plan Ahead
If you're going somewhere where you think the light might be dim, plan to bring a tripod and some high speed film. And if you are lucky to have multiple cameras to use, make sure you choose one that offers the lowest F stop value.7 or 1.5 would be ideal for low-light situations.
Keep Yourself Steady
No matter how open your aperture is, you're going to need lower shutter speeds and a tripod whenever possible. Putting your camera on a tripod will keep your camera steady and will allow you to use even slower shutter speeds. If a tripod isn’t available or appropriate, try resting your arms or camera on available surfaces whenever possible.
Speed Up Your Film
400 ISO film is what many consider to be the industry standard, but a film that slow is going to be a liability in a low light situation. If you're taking pictures of a fixed object then a slower shutter speed and slow film may work, but if you're taking pictures of moving subjects you're going to need 800 or higher. Be warned that as a film’s ISO increases, so does its graininess. Film speeds over 800 are going to show considerable quality loss in the grain.
Let it Blur
As photographers, we often teach ourselves that blur is bad and clear is good. However, the deliberate use of motion blur can be a compelling element of a great photograph; don’t be afraid to let your subjects move around a bit. You may not end up with crystal-clear photographs, but the kinetic energy of a blurry photograph is often far more interesting than one featuring a bunch of stationary objects.
Bracket Your Shots
When it comes to judging light, humans and light meters are often unreliable. If you're in low light and aren't sure your pictures will turn out, try bracketing your shots by taking 3 photos each with different exposure times. Essentially, you’ll shoot one photograph at the shutter speed you think is right, then shoot another with your speed turned to the value just below that, then another with the speed turned to the value just above. This acts as a type of safety net for many photographers. Besides, sometimes under or over exposing a photograph can turn out much better than what the light meter recommended.
Low light photography is an incredible challenge, especially if you’re attempting to do it without the use of a flash. Make sure to understand the nature of your film and camera, use the right equipment and give thought to every shot and your images will likely turn out great. If you do all of these things, you won't be able to tell the difference between your low light photos and those shot during the day. Always focus on having fun while you shoot and don't worry too much about the end result and you'll end up learning to adapt to even the worst lighting environments.