Scuba Diver Australasia + Ocean Planet
PERFECT SPLITS
For me, one of the most wondrous parts of any dive is the moment when the water engulfs my mask as my head slips below the surface. I think it’s the suspense of not knowing what lies beneath, the transitional part of moving from one element to the next that feels so magical, and the thought of what alien creatures I might encounter. That is what draws me to taking half-and-half underwater images. I try to convey to the viewer that majestic feeling in a picture format. Split shots are perhaps the best way I can communicate to a non-diver what it’s all about, to marry a wet and unfamiliar world with a dry and more familiar one. A well-executed over-under shot also seems to be a great crowd pleaser as it has instant “wow factor”.
I’d like to share with you some of the techniques and equipment I use for this type of photography and answer some commonly asked questions regarding equipment, focusing techniques, lighting, what time of day to shoot, and how to stop water beading.
EQUIPMENT
When shooting an over-under scene, you are usually creating a half-landscape, half-seascape scene, so common sense would suggest using a wide-angle rectilinear or fisheye lens to capture the entire vista. I generally use my 14–24mm f/2.8 or 14–30mm f/4 rectilinear lenses for big animals or humans, where
I want to control distortion and create a natural perspective. I use the fisheye lens for reef scenes where the heavy distortion will go unnoticed.
You’ll need a dome port to shoot through: Your usual wide-angle dome port will suffice, something in the region of eight to nine inches is perfect. A bigger port makes the job much easier and conversely, whilst not impossible to shoot over-unders through a smaller port, it does make the job a little harder. It also creates some optical problems – more on that later.
You may want to use your strobes for fill light when shooting into the sun at sunset or sunrise, or to add some colour to that reef.
If you’re shooting a scene where you can’t stand up, it’s a good idea to add a flotation device to yourself and camera. I sometimes strap a swimmer’s kick board under my water housing and use an inflated BCD as a raft to lean on. This will prevent you from sinking when you lift that heavy camera out of the water and it will help you to frame up your shot.
Note: Trying to shoot an over-under with your dive gear on your back after a dive is nigh on impossible!
EVERYTHING IN FOCUS
Set your camera focus points low in the viewfinder and concentrate on getting the underwater part of the scene sharp. Then, use a narrow f-stop such as f/16 or above and the let depth of field take care of the top part. It’s a great technique to use, but why?
To create a half-and-half image you are basically creating a window into another world where light and focus behave on a totally different playing field, especially when shooting through a curved optic such as a dome-shaped port. The interaction of the curved surface of the port and the refraction of the water make what is known as a “virtual image”. The virtual image appears smaller and proportionately closer to the camera underwater. If we were able to see this phenomenon at play it would look something like Fig. 1. Here we can see the camera, the virtual image below the water and the real image above the water.
As depth of field always extends much further behind our point of focus than it does in front, we are maximising our chances of getting
a completely sharp image by focusing on the virtual image underwater.
The smaller the dome port you use, the smaller and closer the virtual image is to your camera and the harder it will be to get under and over parts in sharp focus as the complete image becomes more disjointed.
Figure 2 shows some examples of this. All of these unprocessed experimental pictures were taken at an actual distance from the banner of one metre and were all shot at f/8 with an 8–15mm fisheye lens zoomed to the 15mm end.
As you can see, the bigger ports generally help to make overall crisper images when it comes to over-under pictures. The improvement in clarity above the water is noticeably better with each increase in port size. Regardless of port size, your best chance is to always focus on the underwater part of the scene and stop down your lens as much as you can reasonably go with the light you have to work with. With general port sizes of eight or nine inches, upwards of f/16 is best.