Autofocus systems on modern cameras are quite reliable, and in most circumstances they will allow the user to lock focus easily. But these systems need light to focus, and in really dark situations they can struggle and eventually be unable to lock focus.
The solution obviously is to provide more light. Some cameras do this by firing flash bursts; others by using an AF assist beam (usually a red or green light, sometimes patterned). Those solutions help, but are not perfect either.
So what to do when it gets really dark? Or, when the camera cannot focus at all? One simple solution is inexpensive and extremely effective: use a laser pointer.
Use a laser pointer
A laser emits light, just as a light bulb does. The only difference, at least for the current discussion, is that with a laser all the energy (the light) is concentrated on a tight, bright spot. If this spot is directed to where the camera is focusing, it will provide the AF system with a nice, bright and sharp light source on which to focus. Focusing can become as fast and easy as under sunlight.
The tough part is that it’s not always simple to point the laser exactly to where the camera is focusing. Luckily, there’s a solution for this, too. Many laser pointers come with removable caps that create patterns when mounted in front of the laser beam. Those patterns can be directed in the general direction where the camera is focusing, making things much easier.
Where to aim the laser light
Hold and shine the laser towards the area that is being used for Auto Focus (in other words, frame the laser pattern with the AF box on the viewfinder or LCD). As long as the laser pattern is there, all is well. It’s the reflected light that’s important, not its origin.
This little trick, if performed well, will allow you to focus quickly and accurately even in complete darkness.
Laser pointer safety
A word of warning: Lasers are not toys, and when used poorly, they can be harmful. Be sure to select a class I or II laser, not a class III (the class is always written on the laser). A more intense spot is not needed, and can be dangerous, especially if pointed in someone’s eyes. Even with a low power laser, never shine the laser near someone’s face. Red lasers are less likely to be harmful, and are also better as a focusing aid.