Particles in the water can run your best underwater photos. Here's how to avoid or remove them.
One of the biggest challenges of photographing in water—as opposed to air—is dealing with small dust-like particles that are in the water. They are the enemy of underwater photography.
Even in the seemingly clear, blue, and idyllic tropical waters, there are always some suspended particles that go unnoticed to the human eye. Whatever it is—plankton, sand, or just little bits of muck floating by—it will have a knack for showing up in your underwater photograph. When this particulate is illuminated by your strobes and plays a starring role in your images, it’s called backscatter, and it is the underwater photographer’s arch nemeses.
Note: Strobes, Underwater Housings, and other underwater photography essentials are available at Adorama Camera's Underwater Photography department.
Backscatter in underwater images is an unfortunate reality of underwater photography, but luckily there are ways you can minimize it and sometimes even eliminate it. The first step in preventing backscatter is to learn why it shows up in your images. Backscatter occurs when the light from your strobe hits a particle in the water and is reflected back into your lens. This lights up all the tiny specks that are unnoticeable until your strobe illuminates them, and makes images look like they were taken in a dust storm. Therefore, when eliminating backscatter from your image, you need to figure out how to minimize the amount of reflected particulates between your subject and your lens.
The number one rule of underwater photography is to get close to your subject, and preventing backscatter is just one more reason why this is so important. Being close to your subject limits the amount of water between it and your lens, thereby reducing the amount of potential suspended particles that would be lit up by your strobes. This is a simple first step that should be taken if backscatter is an issue.
Note the backscatter in the marked area. By repositioning my lights to the sides of my camera, I was able to eliminate backscatter in the shot below.
Careful Strobe Positioning
Most of the time, no matter how close you are to your subject, you simply can’t remove all the suspended particles in the water. Therefore, you must do your best to not illuminate the particles, so they don’t appear in your image. This means carefully positioning your strobes so that the light emitted from them does not reflect back into the lens when it hits the particles.
Generally, the farther your light source is from your lens, the fewer particulates you will illuminate. Furthermore, by positioning your strobes by the sides of your lens, you reduce the chance of the light hitting the particles reflecting back into your lens. Longer strobe arms with strobes positioned away from your lens will give you the best results for reducing backscatter.
If you are using shorter strobe arms and need to have your strobes close to the lens, such as when shooting close focus wide angle, positioning your strobes so that they face away from your lens will go a long way towards minimizing the amount of particles that will reflect light back into your lens.
Compact camera users that utilize single strobes with short strobe arms—or worse, the built-in camera flash—often suffer from serious backscatter issues. When the strobe is positioned right above and close to the lens, it illuminates all the particles between the subject and the lens, creating a big backscatter mess. It’s one of the many reasons why internal strobes are not recommended for underwater photography. If you must use your internal strobe, try using a diffuser, which will soften the light and reduce the harshness of the backscatter.
Practice Proper Buoyancy
It’s hard enough to prevent backscatter with all the plankton and other particles naturally floating in the water column so don’t kick up sand and silt and add to your troubles. Be very aware of where your fins are, so that you don’t stir up the sediment. When steadying yourself for an image, use two fingers to balance and position your body so you are facing the subject head down with your fins above you in the water column. Never touch live coral or animals to brace yourself for a shot.
Shooting down current also helps remove a lot of particles in the water that may have been stirred up by divers. By shooting down current, the sand or silt will be washed away from the scene, rather than washed into it.
Shark surrounded by backscatter. Sometimes, it's safer to get rid of the stuff in post-processing than to get in closer, reposition your lights...and become shark food.
Those ain't bubbles: Adobe Photoshop to the rescue here. Each bubble contains a bit of backscatter that's about to go away.
Backscatter begone! With the clone tool deployed, our shark appears to be swimming through a clear, blue ocean.
Good Ol’ Post Processing
In many cases, it is impossible to shoot an image that is 100 percent backscatter free. No matter how far your strobes are from your lens or how clear the water is, it’s often the case that a few specks will show up in the water. That’s where post processing comes in. The clone stamp and healing brush in Adobe Photoshop does a great job of removing backscatter. However, if you have a lot of backscatter, the painstaking process of sitting and removing hundreds of particles in post processing is usually not worth it, so it’s important to try and minimize backscatter as much as possible when shooting.
Backscatter is undoubtedly a serious hassle for underwater photographers. It shows up at the worst times, and can be hard to avoid. However, there are ways to minimize it. Careful strobe positioning is the key: The closer your light source is to your lens, and the more parallel it is to your camera, the more backscatter problems you will have. So keep track of where your strobes are, and with a bit of work in post, you can be backscatter-free.