For Photographers
How do I shoot over-under split shots?
Over-under split shots — the iconic frames that show both above and below the waterline in a single image — require a large dome port, typically at least eight inches in diameter, to physically separate the two refractive boundaries. Use a wide-angle lens at f/16 or smaller to achieve sufficient depth of field across both the close-up below-water subject and the more distant above-water scene.
Set your focus manually on a point just below the waterline, because autofocus rarely chooses the optimal plane for split-shot composition. Apply rain repellent products such as Rain-X or specialized dome-port coatings to encourage water to sheet off the upper half of the dome rather than forming distracting droplets. Shoot in calm water with minimal surface chop, because turbulent water makes a clean horizon line nearly impossible.
Frame deliberately so the horizon line falls roughly at the center or one-third of the frame, depending on whether you want above-water or below-water emphasis. Always expose for the brighter above-water portion of the scene and recover shadow detail underwater in post-production. Practice extensively in calm pool conditions before attempting split shots in open ocean, where waves, currents, and changing light add significant difficulty.