Working with light

Using a laser to focus

Written by Bernard Dery

In low light, a laser pointer can help a digital camera focus faster and more accurately.

Laser pointer

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.

Information on Laser safety

About the author

Bernard Dery

Bernard was born and still lives in Quebec City, Canada. A doctorate candidate in Physics, Bernard works full-time as an optical designer at EXFO, a world leader in telecom tests and measurements tools. His professional interests go from fiber optics to atmospheric data collection and lasers.

His first contact with photography was a Vivitar fixed lens camera that he had purchased at age eight. His interest developed slowly, and for many years Bernard limited himself to family and travel pictures.

Bernard discovered the world of digital photography in February 2004, when he purchased his first digital camera. Developing an interest for composition, he experimented with many subjects: landscapes, nature, cities and architecture.

soon began to invest more time and energy into his new found hobby, finding new and beautiful subjects to capture everyday. His challenge is to capture the mood and emotion carried by a scene as it presents itself to him.

A trip to Italy in
September 2004 fueled his growing interest with numerous magical photography opportunities.

Bernard and his wife like to spend free time near a lake at his family's summer house, where he finds new subjects to capture every day. His interests are varied and include hiking, camping, swimming, boating and reading, as well as most winter

Bernard, known as bdery on forums, uses a Pentax K20D and W80, Canon S2 and a Nikon SQ as a backup.

Thumbnails are of photos by Bernard Dery - used with permission
Copyright Bernard Dery All rights reserved