A new customer asked: “In some of your displayed pictures you have predominately green or red colors. Is this dependent upon the subject or your barrier filter? Do you need different filters to get different colors?”
Great question! The barrier filter determines what colors it is possible to see, while the fluorescence properties of the subject determine what you will see.
The filter – In order to be seen the color has to be transmitted by the barrier filter in the first place. The yellow filter that we use in our diver filter visor, in our above-water filter glasses, and in our photographic filters passes all colors except blue, so with that filter you can see fluorescent greens, yellows, oranges, and reds – everything except blue. (Although sometimes you will see some blue, generally a reflection sneaking through from a very white, reflective subject). So to see and photograph all the colors that you see on the web site you do not need different filters.
The subject – The fluorescence colors you actually do see from any subject are determined by its fluorescence properties. Chlorophyll fluoresces red, so seaweeds, algae, the symbionts in corals, and green leaves and plant stems show up red. Corals have fluorescent proteins in them that are responsible for the colors other than red. You can find a wide variety of fluorescence colors in many other subjects, both above and below water. In many cases the exact underlying source of the fluorescence is not known.