A slower shutter speed is often used in underwater photography to brighten an image, especially in murky or deep water. However, a more challenging technique is using a slow shutter speed to create movement in a still image (often called “motion blur”), compared to normal underwater photographs that freeze the subject with a fast shutter speed. More commonly used in wide-angle photography, this technique can add motion to the subject, the background, or both, resulting in images that can really “wow” the viewer, giving them an impressive feel for the constantly moving liquid world we dive in.

Here are some tips to help you start using a slow shutter speed underwater:

Set your camera’s flash setting to “rear curtain sync”, so that the flash doesn’t fire until just before the shutter closes.

Set your shutter speed to 1/30 sec or slower. Increase your f-stop (f/18 – f/32) to compensate for the increased amount of light due to the longer shutter speed. If the subject is close to the camera, use your strobes on high power to bring out some of its colour. The correct shutter speed and aperture will vary depending on the natural light conditions at the time, but also with the subject and the degree of motion blur you desire.

Avoid shooting at an upward angle towards the surface/sun, as this will result in a large, blown-out white area in the image. You should also try and have some background to emphasise the image’s movement.

If you want to shoot a moving subject (for example, a turtle swimming slowly over the reef), swim along next to the animal at the same speed, and make sure the focus point is on the head/eye while your take the photo. The subject should be fairly sharp, while the reef/seabed in the background will be blurred, giving the appearance the turtle is moving very quickly. If the animal swims past you (for example, a school of fish), then pan with them. (Panning is a technique of moving the camera with the subject).

For a subject that is moving slightly (for example, a lionfish or cuttlefish), move the camera in as close as possible, and take your photo at the moment the subject turns or moves away from you. Moving your camera forward, together with the movement of the subject, will give you a nice effect. The long spines of a moving lionfish for example make a great subject for this technique.

Shooting macro with motion blur is a bit trickier than shooting wide-angle. For this, panning with the subjectis the most common technique. A subject that moves with an elaborate motion (for example, juvenile sweetlips or a swimming flatworm) are great for a slow shutter speed, but may require a number of shots to get it right.

A fun technique is using a zoom lens to create “zoom blur”. For this, you’ll need the correct zoom gear/ring for the wide-angle lens in your housing (for example, Tokina 10-17mm, Canon 8-15mm, or Nikon 12-24mm).

Get very close and keep the subject in the center of the frame, then zoom in and focus. As you shoot, you must zoom out in the split second between the shutter opening and closing, which can take a bit of practice to get used to. This can still be achieved using a lens with a fixed focal length (for example, Canon 15mm, Nikon 10.5mm, etc.), by pulling the camera back towards you as you take the shot.

With the subject in/near the center of the frame, as you take your shot try spinning the camera slightly to one side in between the shutter opening and closing. This will give a “spin blur” effect, leaving the center of the image relatively sharp. A slight combination of zoom and spin blur can produce a stunning result.

Have a practice using a slow shutter speed on land first with your camera and housing and you’ll soon get comfortable with this fun and exciting technique, which when used correctly can really liven up your images.

Christian Loader (29, UK) is a professional photographer for Scubazoo Images. He has worked extensively throughout Southeast Asia as an underwater videographer and photographer, and is currently based in Kota Kinabalu, Sabah, Malaysia.