Focus lights are a critical tool for underwater macro photographers using strobe or flash lighting to help the camera achieve sharp focus.

How do focus lights work?

The autofocus system relies on details within the scene to determine correct focus. It
 works very well in bright conditions, but there is
 much less ambient light
 underwater. Your macro
 subject might be shad
owed, camouflaged against a nondescript background or spotted during a night dive. As a result, your camera may struggle to find focus in these dark shooting conditions. A focus light delivers brightness to the scene and allows for sharp focus.

Most manual macro shooters will use a fast shutter speed and high aperture to minimize light reaching the camera sensor. As a result, photos will only show the light from the strobe flash and not from the lower-powered focus light. This is advantageous at night when shooting critters shy of white light. The diver can approach, compose and focus the shot using the red light mode of the focus light. When the strobe flashes, the scene is captured in white light with no red light visible. On top of that, the focus light makes a great primary dive light.

Photographers using a constant light source to illuminate their images don’t need to worry about a focus light since they already have a bright light on the subject. No strobe flash is needed.

Which focus light is best?

Focus lights do not need to be extremely powerful. Lumens range from 1,000 to 4,000, with the stronger lights better suited for additional use as a video light or during night dives. Talk to your local dealer about the best light for your system.