Underwater dome port
Also known as: dome port, over-under dome, split-shot dome
A large curved window for an action camera housing that corrects underwater lens effects and enables half-above, half-below water split shots.
Updated
What it means
Flat camera windows bend light at the water surface, which narrows the field of view underwater and adds distortion at the edges. A dome port is a large curved acrylic or glass window placed in front of the lens. It restores a wider underwater view and, because of its size, makes over-under shots possible.
Over-under, or split shots, show the world above and below the waterline in one frame: a surfer on top and the reef below, or a boat above with swimmers beneath. These images are some of the most striking in water sports.
Dome ports attach to a dive housing or directly to some action cameras.
How it works in practice
For split shots, hold the dome half in the water, keep the waterline steady across the frame and choose bright, calm conditions. Splash the dome with water to keep the top half free of drops, or wipe it with a soft cloth.
In surf, a dome lets you film waves breaking over you, with the lip visible above and the turbulence below. A floating grip or handle makes the large dome easier to control.
Clean, scratch-free domes matter, since every mark shows on the large curved surface, especially when the sun is in front of you.
What to watch out for
Water droplets on the upper half ruin the split effect. A hydrophobic coating or wetting the dome before each shot helps, as described under water droplets on the lens.
Domes are bulky and catch waves, so they need a firm grip and a wrist strap. Scratches on acrylic domes are common, and careful storage in a padded cover saves them.
Focus can be tricky with domes on some cameras, because the dome creates a virtual image very close to the lens. Test before an important trip, ideally in a pool, and check the edges of the frame for softness.
How RawClip handles it
RawClip uses your split shots and underwater clips as recorded and does not correct color. Upload them with your surface footage, and the AI picks the most striking moments for your highlight.