Figure 3. Photograph taken outdoors in the dark on a moonless night. The light levels are equal to that found in rural areas without artificial lights. Despite being at the limits of human vision, the quality is quite high. Image was taken with a Nikon D200 fitted with a 50 mm f1.8 lens. Exposure was 30 seconds at ISO 3200. Dark frames (photos of pure dark) were taken and subtracted from the images to reduce noise. The D700 purchased for this expedition is eight times more sensitive with far less noise, and so could take this same image in about 4 seconds. Image courtesy of Bioluminescence Team 2009, NOAA-OER.