We often get asked “Do I need an automatic (or “Auto”) light?”.
Auto lights offer two distinct features over other underwater lights: The Auto light automatically adjusts brightness to the optimal amount needed to see or shoot pictures/videos. This will save battery power for longer run time and preserve your eye’s natural low-light vision. A light sensor on the front face of the light constantly measures the amount of light reflecting back from the object. The light will dim when aimed at close-up objects and increase brightness [to full brightness] at far away objects. Auto lights also include manual brightness control if you prefer consistent light output.
The other purpose of the Auto light is to detect when your external flash (strobe) fires and temporarily turns off the photo-video light for one second. This prevents unwanted shadows and backscatter that may be caused by the photo-video light. You can enable or disable the Auto Flash detect feature if you want to use the photo-video light in combination with your external flash.