Using Filters in Underwater Photography
Filters are not new to underwater photography, but they have come of age with the digital revolution. On land, the opposite has been true. There, as the capabilities of digital cameras and software have grown, so filter use has become less popular. Underwater, the situation is different because we’re using much stronger filters than on land because we have to deal with much bigger color shifts. Furthermore, filter photography underwater benefits hugely from the adjustable white balance of digital.
When used on film cameras, filters were hit and (mostly) miss; but now we can fine-tune every shot making them one of the most dependable of all underwater photography techniques. They are now mainstream and we truly have another way to shoot colorful underwater pictures.
Filters produce colors that penetrate deeply into the shot, making them ideal for wrecks and reef scenes stretching away from the lens
Why Use Filters for Underwater Photography?
Filters are an alternative to shooting with strobes, not a replacement. Like any techniques, they are about adding another option to your arsenal of skills—something to be used with suitable subject matter, in suitable conditions. They also provide the chance to take a different type of image and diversify your portfolio.
Probably most exciting for photographers is that filter photography adds color to images in a different way to shooting with strobes and many of the most memorable filter images are ones that just can’t be replicated with strobes.
One question we get asked a lot is what is the advantage of using a filter, compared with just using the camera’s manual white balance alone. When you are very shallow, just below the surface, in the top 2-3m (6-9ft) then white balance alone is absolutely fine. However, once you are deeper than 3m (9ft) the advantages of a filter become more and more apparent.
Filters allow you to dive without cumbersome strobes and arms yet still get very natural colors easily
Subjects for Filter Photography
The best subjects for filters are coral gardens, divers, wrecks, big pelagics, and schools of fish. Filters work best on sunny days, when there is lots of light, although now that most cameras perform very well at medium and high ISOs, they can be used in far more conditions than in the early days of digital. One of the most obvious differences in filter images is that color penetrates deeply into the shot, making them ideal for reef scenes stretching away from the lens, a school of fish coming towards it or a shipwreck or big animal that is just too large to light any other way.
No underwater filter can work at all depths because the filtering effect of seawater increases rapidly as we descend. The goal of many dedicated underwater filters is to create a work with the camera’s manual white balance to give as wide an operating window as possible. No photographer wants a filter that is perfect for the wreck at 50ft (15m) and stops them photographing the group of dolphins at the surface at the end of the dive. Top end filters, like the Magic Filters, are designed to work at the surface too. That said, filter photography works best when shallower than 50ft (15m), although with less colourful subjects you can push this a little deeper (the wreck shown is in 70ft of water).
The general rule is to shoot with the sun behind you—but rules are there to be broken!
Filters bring color and detail to large shoals of fish, which strobes just could not cover
Combining Filters with Manual White Balance
Although we can white balance in post, we get noticeably better results if we set the camera’s white balance manually underwater. This is because RAW files are not really as “raw” as we sometimes like to think. Big adjustments to white balance in post do create noise and a lack of colour depth, which are not visible if those values are already locked into the file at the time of shooting.
Underwater we can set white balance against a white slate or grey card, but most of the time a neutral colored section of reef, wreck or sand is fine. As long as it is done at roughly the same depth as the subject. Common problems that cause trouble in setting white balance are when the camera is under exposing the white balance target, the target is in shadow, or we are too deep. If it won’t set at all, you can still shoot and fix it in the RAW converter (although this will not give the absolute best image quality). Small adjustments in post processing won’t affect the image quality, so as long as you have set it underwater it will be fine to make small corrections.
Filters help increase the contrast between the foreground and the blue water background
Photographing with Filters
The key to shooting successfully with filters is to appreciate it is completely different to shooting wide angle with strobes. With filters the golden rule is to always shoot with the sun on your back, so it comes over your shoulder and illuminates the subject. The direction of light must be your first thought before every shot. This means you cannot shoot every angle on each dive and may need to dive a static subject, like a wreck, at different times of day to get the perfect shot of every feature of interest.
It is worth shooting RAW + JPG with filters as many cameras process this type of images much better than third party software like Adobe Lightroom can. This is especially true of Canon cameras, which can add much more “tint” in camera, than can be added within the limits of Lightroom. If you shoot RAW + JPG be aware that Lightroom will download, but not usually show you the JPGs (you have to find them in your folders). Setting the white balance causes concerns amongst new filter shooters. The key is to practice on land (although with the camera in the housing) so you get used to the procedure for setting it. This does vary between cameras.
Magic Filters are available in various sizes for mounting in front or behind most lenses, and also for GreenWater, too
A strange effect of filter photography on some dives is the LCD screen can be a bit misleading on colors. I have had photographers show me their filter shots after a dive disappointed that they could not get the filter and white balance working. Then when they see the images again on the camera at the surface they are really pleased. So even if the results look a little off underwater, keep shooting, you will probably get a pleasant surprise when you download.
The best filter shots are taken when the light is right for the subject
The main advantage you see when using a filter, as opposed to white balance alone, is more subtle variations of foreground color, and most noticeable, you get these colors with a richer blue background. Many photos taken with manual white balance are characterized with a completely washed out background water color. Filters produce a much richer blue. A strong blue background is an important aesthetic element in an underwater photograph. Ask anyone what color the sea is and they will tell you it is blue!
Finally, there is the hidden pleasure of filter photography to enjoy: Leaving your strobes on the boat and enjoying the freedom of a maneuverable and compact rig. Ahh, the joy of diving!
Filters can also be used with standard lenses using high-ISO capability, which creates useful depth of field