Edge Lighting:

Figure 1: edge lighting with one strobe (side view or top view, depends on what type of lighting you want: balanced or unbalanced.)

Figure 2: edge lighting with dual strobes (top view)

What do you see in the diagrams above?
Answer: the subject (orange fish) _is illuminated_
and the most of the water between the lens and the subject _is not illuminated_.

What does this do for your pictures?
Answer: if your strobes are aimed correctly, it can eliminated alot of the backscatter even on those murky <5' vis days we sometimes get in monterey.

What's backscatter?
Answer: Out of focus and illuminated stuff (light blobs shaped like the aperture of your camera's lens) in the water between the subject and the camera lens.

To use this technique, you have to visualize the cone of light your strobe projects when fired.

Strobe beam angle visual aid

Figure 3: examples of strobe beam angle visual aids


  • gives you a quick visual confirmation of the cone the strobe will cover
  • allows you to better visualize what the strobe will illuminate when fired

What you'll need:

  • white electrical tape (3/4" wide)
  • an exacto knife
  • a protractor
  • a piece of scrap plastic
  • the backing from a plastic sticker


  • cut a 5 or 6 inch piece of white electrical tape
  • stick it to the sticker backing making sure to keep it straight lengthwise
  • look up the beam angle of your strobe (B_angle)
  • divide the beam angle by two (X = B_angle/2)

Figure 4: Cutting the visual aids from the white electrical tape

  • place your protractor on the long edge of the tape so that it reads 90 minus X degrees (yellow protractor) and make a cut with the exacto
  • flip the protractor and place it on the opposite side of the tape where the first cut ended (green protractor) and make your second cut
  • repeat previous two steps until you have four triangles per strobe
  • set you protractor to 90 degrees and make the centerline cuts on each triangle (blue protractor)
  • place the cut pieces of tape on your strobe at 90 degrees to each other with the center line of the triangle on the centerline of the strobe (see figure 5)

Figure 5: Strobe with visual aids in place

See how the cone of light matches the visual aid.