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Strobes help you freeze the action, and capture creatures on the move like this lyretail anthias, Pseudanthias squamipinnis (Settings: f/14, 1/30s, ISO 100)

Light it up! Get to grips with the basics of using strobes to release and capture the vibrant colours hiding underwater.
 

Have you ever wondered why your underwater photos always come out so blue and never have that beautiful colour other photographers seem to produce? Well, an artificial light source is the answer, and, in my opinion, strobes are the best underwater photography investment you will ever make.

Water is much denser than air and the moment we submerge ourselves underwater, colours start to disappear. The deeper we go, the more colour is lost.
 

Strobe Basics

Power

Strobes work by giving light at different power settings. Most, if not all strobes today will have a power output dial. Each power setting refers to the duration of time that the bulb emits light, normally between 1/1000 –1/500 of a second. The lower you set the power setting, the shorter the duration that light will be emitted. Strobes need to recycle after being fired, so recycle time is a factor to consider when making a purchase.

The more power the strobe has, the better. Power in strobes is measured by a guide number – the higher the guide number, the more powerful the strobe.

Diffusers: Power and Angles

Check to see if the guide number is with a diffuser or not, since a diffuser will reduce the guide number. When you look at the power of a strobe, also have a look at the angle of coverage. This refers to the width of coverage of the light that the strobe puts out. The wider the lens, the wider the angle of coverage needed from the strobe – you need the light to fall over a greater area. Some smaller strobes will have a smaller angle of coverage. Diffusers help increase the angle of coverage, which is better for wide-angle photography, they also lower the light, the contrast, and soften the shadows.

Manual vs. Automatic

The idea behind manual strobe control is that you set the aperture, shutter speed, and strobe power to fit your scene. You have information at your disposal that the camera simply does not have, namely the distance between the strobe and the subject, along with the strobe power. By contrast, through-the-lens (TTL) strobe control is a method where the strobe communicates with the camera to obtain the right exposure automatically.
 

Good strobe positioning makes a difference as with this full-frame macro of an expressive blenny (Settings: f/25, 1/200s, ISO 100)

Positioning

Getting creative with light is always the end goal of underwater photography, but understanding the basics of lighting and strobe positioning is very important to getting richly colourful images.

Whether you start off with one strobe or two, it’s the position and angle that will determine the quality of your lighting. Strobe positioning can also result in something called “backscatter”. This is when the particles in the water between the lens and the subject are lit up – and is an underwater photographer’s worst nightmare. Strobes are therefore connected to the housing on variable arms, extending away from the camera at adjustable distances, allowing you to light the subject in a way that avoids generating backscatter whether you are photographing macro or wide-angle subjects.
 

The key to good photography with strobes is balancing the artificial and ambient light (Settings: f/13, 1/100s, ISO 100)

Basic Wide-Angle Setups

Having the most powerful strobes on the market will still only light up a subject a few feet away, so it is impossible to light up an entire reef. We need to balance the strobe light in the foreground with the ambient light in the background. This is an important skill to learn if you want to shoot wide-angle successfully.
 

When shooting close-focus wide-angle, you need to light just the subject, not the foreground or background (Settings: f/16, 1/160s, ISO 100)

Basic Macro Setup

One of the main lighting rules we learn is not to aim strobes directly at the subject as you will end up lighting the particles between you and the subject. In macro photography this is less of a problem, as we tend to be much closer to the subject, which significantly reduces the chance of backscatter. We can now start to use light more creatively.
 

Creative use of strobes can make your subject pop, as with this striking shot of a clownfish in its anemone (Settings: f/13, 1/160s, ISO 100)

Strobe Tips

• Get as close to your subject as possible.
• The more powerful the strobe the better.
• As you get closer to a subject, bring the strobes in closer to the housing.
• If you see backscatter while reviewing your image, push the strobes out wider.
• Let conditions help determine the best kind of photos to take in order to minimize backscatter.
• Always test the strobes before a dive (last thing you want is a flat battery at the start of your dive).
• Use diffusers to soften the light when needed.

Most importantly, once you’ve mastered the basics, try to get creative. Photography is all about how you use the light.
 

With the right strobe positioning, super macro images come alive with colour and texture (Settings: f/25, 1/100s, ISO 100)
 

About the author: Mark Fuller started diving when he was just 13 years old in South Africa, where he was born and raised. After settling in Israel and working as a diver at a fish farm in the Red Sea, his passion for underwater photography began. Living close to Eilat at the northern tip of the Red Sea, Mark is able to dive and concentrate on his photography all year round. Mark is always pushing the limits in underwater photography, practising new techniques, capturing behaviour and perfecting his portrait, macro and super macro photography. He also enjoys dabbling in the wide-angle opportunities the Red Sea has to offer. www.mark-fuller.com