A look at how filters can work their magic in water photography.
Words by Urth HQ
Water is a favourite subject for many photographers, but it’s not without its challenges. Whether you shoot watery scenes on dry land or you capture images below the sea’s surface, a lens filter is a must-have in water photography.
If you take photos of water or wet surfaces, glare and reflections can be a problem. A polarising filter eliminates these by reducing scattered light. It also boosts colour intensity and lets you capture details on the water, both above and below it. Using a polarising filter gives you more visually appealing shots, reflections or haze can be banished from the sea to give it an alluring, transparent feel.
When you use a polarising filter, it cuts out the equivalent of around 2 f-stops of light. This means you’d need to compensate for 2 f-stops of light exposure with this filter on your lens. By reducing overall exposure, the photographer can darken an image, adding intensity and clarity to a scene. A polarising filter reduces glare and reflections on water or rocks, it can also make water appear transparent.
When you rotate a polarising filter, you adjust how much polarised light you block out. The maximum polarisation effect is when the lens is pointed at 90 degrees to the sun or other light sources. To achieve this, make an L shape with your first finger and thumb, pointing the thumb at the sun. Where your pointer finger rests (you may need to rotate your wrist) will indicate where the polariser has the optimum impact. Of course, this doesn’t always work for every scenario, especially if you use a wide-angle lens, so take it (literally) as a general rule of thumb!
When water is moving — think babbling brooks, gushing waterfalls or choppy oceans — you can produce truly ethereal, smooth and silky shots using an ND filter on the end of your lens. These dreamy effects bring water scenes to life, adding atmosphere and drama.
This transparent filter reduces light exposure entering your camera lens. This allows you to shoot using wider apertures and longer exposures, without overexposing an image in bright conditions. You can control how much light you want to block from your camera lens with different filter strengths or densities. Filter strengths are represented by f-stops. A photographer will find an ND filter useful to achieve a balanced exposure between an image’s foreground and background. In bright light, this filter produces a shallow depth of field by reducing light exposure with a wide aperture. This won’t overexpose your scene.
By blocking light from your camera lens means your camera needs to be exposed to light for longer periods of time, whereby you have to open the shutter for longer to allow the correct amount of light to enter your camera. Thus, using and ND filter lets you slow down the shutter speed or use a wider aperture in bright daylight. Letting in light slowly allows moving things, such as clouds or ripples on water, to blur or blend in. To blur water or clouds, a good choice of neutral density lens filter is a 6 to 10 f-stop. This gives you a decent exposure time of up to 4 minutes. It is advised for these long exposures to use a tripod if shooting on land.
Without a neutral density filter, a camera would struggle to achieve a small enough aperture to capture these same effects.
Whether you have a penchant for shooting shipwrecks, surfers, coral reefs, big fish or schools of tiddlers, what lies beneath the sea makes for an exciting playground for any photographer. Yet, shooting under water is a different ball game compared to snapping on dry land, presenting a whole new set of challenges.
For starters, when you go underwater, you lose colour. Water acts like a natural filter, with red disappearing first, followed by orange then yellow. Since red is lost first, red filters are the most frequently used for shooting below the sea. This is especially the case in blue water. If you’re in green water, you may prefer a magenta filter. It’s good to know — you can lose around 1 to 1 1/2 stops of light using an underwater filter.
Underwater filters are designed to bring colour and contrast back. They work by reducing blue light so that it becomes more even with the amount of red light.
It’s also worth noting that colour changes underwater depend on depth and distance. When shooting at very shallow depths, you might be able to get away with just adjusting the white balance of your camera. Go deeper than around 9ft and you’ll notice visibility worsens, and how everything looks darker and bluer. This is where a filter really comes in handy.
Lots of underwater photographers use strobe lighting to bring colour back to images. But, it’s often more convenient to use a colour-correcting filter than carrying strobes around. Plus, strobes will only bring colour back to the immediate foreground and not further into the distance. If you do use a filter, don’t combine it with a strobe, and remember to turn your flash off.
An underwater filter will reduce the amount of light available for focusing and exposure, so you may need a slower shutter speed or larger aperture. Filters are best suited for shooting underwater during the day and at shallowish depths. When your camera is no longer able to detect red light at big depths, typically around 30ft underwater, you won’t gain any benefits from using a filter. The bottom line is, a filter won’t give you colour if there’s none there already.
When using a filter in water photography, shoot with the sun behind you and point your camera down at an angle of 45 degrees. Think about how you’ll mount your filter, as there are various options to choose from, including threaded filters that mount on the front of your lens, or gel filters that mount on the back of your lens.
With all this in mind, consider what you want to shoot before deciding which filter or item of equipment is right for you. Other factors to ponder include the depth you intend to dive, the quality of the water and how much sunlight there is around. Having more than one filter type to accommodate changing conditions underwater often makes good sense.