Always been confused about your camera settings and how they relate underwater? Here is a quick explanation for you to understand the basics.
The size of the stop is one factor that affects depth of field. Smaller stops (larger f numbers) produce a longer depth of field, allowing objects at a wide range of distances to all be in focus at the same time.
Shutter speed or exposure time is the length of time a camera's shutter is open when taking a photograph. Very short shutter speeds can be used to freeze fast-moving subjects, for example a swimming fish. Long shutter speeds combined with a small Aperture will allow for a great depth of field. This can be useful when taking a scenic reef photo where you can stabilise the camera.
The ISO speed determines how sensitive the camera is to incoming light. A high value gives you an opportunity to get sharp photos in low light environment like a cavern. However, the higher you set a camera's ISO, the more noise you introduce into your images. Along with shutter speed and aperture, ISO is one of the three factors that determine your picture’s exposure. Finding the right balance between these three settings is key to getting the perfect shot.
Strobe / Flash
An external underwater strobe, also known as an underwater flash, is very important in underwater photography. The light will help to recreate color and illuminte, as light disappear with depth. It also allows you to reduce backscatter, compared to an internal flash, and enables you to try different lighting options. If you are using a built in flash, note that since the light is coming directed straight on the object, backscatter can occur. A built in flash would be useful for close macro photography to light up small cracks in the reef.
White balance is a way to tell you camera what the actual colors are. As color disappear with depth you photos will appear green and/or blue without artificial illumination. By setting the white balance you take pictures with close to natural colors at shallow depth without the help from a strobe. This is a good option for compact cameras without strobes in clear water to capture scenic photos. Go to cameras white balance setting - at depth, hold up a white slate in front of the camera - press the adjustment button.
Tips & Tricks
GET CLOSE - Avoid using zoom underwater as the light has to travel further. Due to poor stability, pictures will often then become blurry. Try instead to get closer, which also will remove backscatter when using artificial light.
COMPOSITION - Think about having a foreground, subject and background. This creates a depth of field and a more interesting photo. Avoid taking pictures on subject from above as they will come to appear two dimensional. A good rule of thumb is to get at the same depth as the subject or slightly below. Keep in mind to have the sun in your back unless you are taking a silhouette photo.
GOOD BUOYANCY & PATIENCE - Having good buoancy is essential to be able to take sharp pictures. This also allows you to get close to the reef or the bottom while avoiding touching and damaging the reef. Take your time to accomplish buoyancy and get in position for the shoot, it is worth it!
It doesn’t take long to learn how to take a descent underwater photo. But with some help from us, you will get there quite quickly. Read more about the underwater photography course here.