I never tire of creating over-under water images, a technique advanced and popularized by National Geographic photographer David Doubilet. The over-under or half and half image provides a window into two very different worlds in a single frame, and if done well can be a powerful tool in fostering a greater appreciation for the other 71 percent of our planet.
The technique requires a bit of patience and the right conditions to pull off, so when setting out to create compelling over-under's here are a few things to keep in mind.
Lenses and Ports
I realize I’m stating the obvious, but just in case, wide-angle and fish-eye lenses are ideal for this technique as they provide more depth of field. Whichever you opt for, you’ll need to place the lens behind a dome port, as opposed to a flat port. Dome ports come in different sizes, and while over-unders can be created with small ports (4 inches) I prefer larger ports (about 8 to 9 inches) as they allow more flexibility when dealing with an uncooperative surface. Larger ports push the water farther away from the lens minimizing the thickness and distractibility of the water line in the final image.
I tend to prefer shooting over-unders with ambient light, but of course this is not ideal in all situations, especially not at sunrise or sunset when you’ll need a bit more light below the waves. While over-unders can be taken at any time of day, an even amount of light between the terrestrial and underwater worlds takes place midday. However, shooting at this time of day will show harsh shadows that can be filled in with strobes.
Before jumping in, I usually set my aperture to f/16, shutter speed to 1/200 s, and ISO to 200. Once in the water I adjust accordingly and expose for the sky. A smaller aperture provides more depth of field for both the underwater and topside scenes, while the shutter speed needs to be fast enough to deal with the fluid environment you are at odds with.
More often than not, I find myself creating over-unders in shallow water. If this is the case, lose the fins and find a place you can stand or kneel without damaging the reef. If I do decide to use strobes I like to have floats attached to the arms for better buoyancy and overall control.
One of the most frustrating aspects of creating over-unders has to be the unrelenting water droplet. There is nothing worse than having a great shot ruined because of a droplet. Sure you might be able to fix it in post, but it’s always better to get the shot right in camera. There are several ways to deal with water droplets depending on your preference. Saliva, potato starch, and a simple dunking technique are some of the tools at your disposal. Something to keep in mind is that glass ports tend to cope with water droplets a bit better than acrylic ports, but are more expensive and far less forgiving to scratches.
Besides water droplets, the second most frustrating aspect of trying to create an appealing over-under image is the lack of an underwater subject. While the conditions may be perfect and the topside subject interesting, without an underwater subject more than likely the image won't work. But, a little patience can go a long way. Give it some time, usually something will pass by if you wait long enough. It's important to note, having an interesting topside subject is also very important, but sometimes a dramatic sky is enough.
Once you find the ideal underwater subject, be sure to focus on that portion of the frame — not topside.
I hope it goes without saying, good water clarity is an important element in creating over-under images.
When I first started out, I did so under the assumption that the surface line should be as straight as possible, however, as time went on I realized a wild surface line adds a bit more interest to the final image.
Creating over-unders are a great way to bridge the gap between two very different environments and are a perfect technique for those that don’t scuba dive, but like underwater imagery. Sure, they require a bit of patience, but are well worth the effort. If you are just starting out, try shooting without strobes at first, and add them as you progress. Despite some of the frustrations that come with over-unders, they are a great way to add a bit of diversity to your portfolio.