No backscatter with underwater fluorescence photography!

Posted On: Monday, April 13, 2015

Backscatter example, fluorescence (c) Charles Mazel

A cool benefit of underwater fluorescence photography, besides the obvious one that the technique produces fantastically beautiful images, is that there is no backscatter! Backscatter is normally a major headache for underwater photographers. The light traveling from your light source bounces off particles in the water between your camera and the subject and back into your lens. The result is little bright spots throughout your photo.

But with fluorescence you are not photographing the excitation light you direct toward the subject. The only reason you send out that light is so that it will be absorbed and turned into new wavelengths (colors). You use a barrier filter to block excitation light reflected from the subject. That filter also blocks excitation reflected from particles in the water! The light emitted by the subject as fluorescence does not cause backscatter because, from the point of view of the camera, it is hitting the back side of the particles and not reaching the lens.

The white light and fluorescence photos below illustrate this nicely. The two photos were taken within about 30 seconds of each other on a windy night with lots of suspended sand particles. In the white-light image you can see lots of spots while the fluorescence shot is crystal clear.

(click for larger image)



3 Responses to “No backscatter with underwater fluorescence photography!”

  1. Hi Charlie,This phenomena I have shown in my YouTube movie in Sept.2013 already. You can watch this from 2:29 minutes >
    This fact is important, since it is not necessary to place the torches in a far distance to the camera. The illumination of the objects can be in the same angle (axis) as the camera. This is in contrast to the illumination with white LED-torches and stobes.
    Best greetings Horst

  2. Hi Charlie,
    anyhow both reports are very important for many people, since they do not know how to place their strobes or LED-torches under fluorecence conditions.
    Therefore your report is very important. In contrast only few people have time for a look into my movie – they get soon tired.
    Personal regards

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