Expedice Jižní Pacifik

Fascinating fluorescence at night

Expedition leader Heiko had brought along some special technical equipment to photograph the beautiful fluorescence of the corals underwater at night. The effort required for such fluorescence photos is quite high, but the results are worth it.

A special yellow filter had to be screwed onto the lens of the underwater camera (Canon EOS R with 35 mm macro lens). The underwater flash had to be fitted with a special blue filter and a lamp was needed to provide strong blue continuous light so that the camera's autofocus could focus on the coral at all. In order to see the fluorescence in the blue continuous light through the diving goggles, a yellow glass had to be folded in front of the diving goggles. Finally, we attached a normal underwater lamp to the underwater housing so that we had a normal light as well as the blue light.

With this somewhat unwieldy construction, diving was a bit of a challenge, but as soon as a beautifully fluorescent coral became visible, the effort no longer mattered. There are hardly any published fluorescent images taken in the open sea. Most of the photos are taken in aquariums.

Fluorescence is said to help corals at greater depths (up to 165 m) make better use of the limited light. However, there are also many species that live in shallow water.