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Flitslicht of videolicht voor onderwaterfotografie

Video light or flash light for underwater, which is the best option?

Almost all the questions I get about underwater photography are about light. This is no surprise. Almost everything that can go wrong in your photo is light-related. One of those frequently asked questions is: video light or flash light for underwater, which shall I choose?

Why do you need additional light underwater?

Anyone who has ever stuck their nose underwater knows that it is darker under the surface than above. 

Water absorbs light. The deeper you dive underwater, the less light can penetrate the water. In addition, colours become less vivid and some colours disappear altogether.

You can use video light or flash light for underwater use to:

  • putting your subject in the spotlight, literally and figuratively.
  • retrieve colours lost through depth, first red and orange
  • separate your subject from the background, by making the background darker or even black (see the fish example below)

In the Netherlands, you notice the difference from light to dark immediately, you dive into the dark, so to speak. In tropical waters abroad, this is perhaps less obvious. But as soon as you want to take a photo, you notice it immediately:

Without additional light, you will get dark or blurred photos with a green or blue colour cast.

So for a sharp, clear photo, you need light. You have a choice of:

  • video light
  • strobe light
Videolicht of flitslicht voor onderwater

Video lights

The name says it all, a video lamp is most commonly used for shooting video. But of course, you can also use it to take photos.

Because you lose light so quickly underwater, it is important to use as strong a video lamp as possible. The amount of light is indicated in lumens.

My video lights have 8000 lumens. I can use them fine for macro or a close-focus wideangle, as long as I stay close to my subject. 
Want to photograph something further away from my lens? Then I quickly run out of light.
If you have more budget for more lumens, choose one so higher, preferably one that is incrementally adjustable in strength.

Can't you just take pictures with the light from your diving lamp then?
Often a diving light is not bright enough; you need less lumens to see than to photograph. Your eyes are better at picking up light than your camera. The beam of light from a diving light is often bundled to create a tight beam that allows you to clearly highlight something underwater. The middle of the light beam is therefore often brighter; you have a "hot spot" in the middle, so to speak. This does not allow you to create even lighting. You can see an example of this in the photo below.
A video light has a better spread and distribution of light.

Videolicht of flitslicht voor onderwater

Flash units for underwater photography

A waterproof flash suitable for diving works like a normal camera flash and gives a powerful, short burst of light. The flash connects to the camera through flash cables. These sit in the camera's water housing at one end, where they pick up light from the camera's flash itself. With that light signal, the flash gets the signal to fire the flash at the right moment.

This light is so strong and short that it can "freeze" the movement of the subject in a photo.

This freeze effect applies not only to movement of the subject, but also to movement of the camera/yourself. Without that freeze effect, you run the risk of a slow shutter speed which is the cause of your blurred photos.

If you have a camera where you cannot set the shutter speed yourself, like the Olympus TG, then a flash is the solution to your blurred photos. 

The power of a flash is represented by the guide number

The guide number ranges between 20 and 40, the higher the number the stronger the flash.

Buying an underwater video light or strobe

If you want to buy video light or flash light for underwater photography, what do you keep in mind?

  • The power of the strobe
    For a flash, this is shown as guide number, for a video light in lumens. The power of your video or flash light is a crucial factor to consider. A brighter light gives you more flexibility when shooting, giving you enough light even in brighter water.
  • Beam angle
    How wide is your beam of light? If you only take macro photos, then a smaller angle will do. If you also take wide-angle photos, it may make sense to choose something with a wider coverage angle. From 100 degrees and up, you can then use it well.
  • The reload speed
    There is nothing more frustrating than waiting for a flash to reload so you can fire your next shot. If you shoot action, I strongly recommend buying a flash with the highest recycle rate you can afford. At full power, one-second charge time is ideal and two seconds is reasonable. If the flash has less power, the recycle rate should naturally improve.
  • Colour temperature
    The colour temperature of a flash determines how warm or cool the emitted light is. Most flash units range from 4600 to 5600K - with 4600 being warm and 5600 on the cooler side. If you are working with two different flash units, it is important that they are both the same temperature/colour.
  • Flash size
    A trade-off between size, weight versus quality. If you travel a lot, it is useful to consider the weight in your hand luggage. A smaller flash is also easier to aim and makes your overall set-up smaller so it is easier to handle.
  • Battery/charger
    How long can you use your light? For a video light, it's important to know how long the light will stay on at full or half power, and in flash how many shots you can take. Can you recharge the batteries on the go or do you need spare batteries

Advantages flash over a video light for underwater photography                          

  • A strobe is much stronger than a video light
    You can keep more distance from your subject with flash light. Because your light is stronger, it can cover a greater distance.

  • A flash can "freeze" your subject
    The bright burst of plenty of light combined with your shutter speed allows you to photograph your subject in sharp focus. All movement, both that of your subject and yourself is "frozen". A video lamp gives less light, so the shutter has to be open longer and will soon give motion blur. (You can of course open your aperture further or increase your iso, which can also have drawbacks)
  • Animals are less scared of flash than of continuous light
    With a flash, underwater photographers are less conspicuous to animals underwater. Some marine animals are sensitive to light and are startled by bright light. It is easier to photograph, say, a seahorse with a flash than with constant light. With constant light, it quickly turns away from you. Skittish/shy animals also flee from your continuous light faster.
    Because your video light has a contrast between yes/no light, a fish sees the light coming. It sees light/shadow moving and flees before you could get close enough for a photo. With a flash it doesn't have to be frightened by this, the light is only fired when the picture is taken.

  • Langere accuduur
    Because the flash is only used when taking the picture, the battery generally lasts much longer than a video light that is on for much longer. Usually, your video light is on for much of the dive.
  • No effect on shutter speed
    Because your flash has no effect on the shutter speed, you can set the exposure of your foreground and background separately. Below are two rubber ducks underwater in a swimming pool. The ducklings were photographed from almost the same distance. The ducks themselves have the same exposure, while the background is lighter on the left (1/50sec) than on the right (1/100sec).

Disadvantage of an underwater flash

One of the biggest drawbacks of a flash is that you have to learn how to use it. Combining ambient light with your flash can be a challenge.
Want to learn more about shooting underwater and adding extra light?
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Benefits of an underwater video light

So doesn't a video lamp have any advantages? Yes indeed!

  • A video lamp is much easier to use! Because the light is already on, you can see where the light is falling on your subject. You can see where the shadows occur and whether your subject is lit at its best.
  • If your camera shows the exposure on your life-view, you can even already check that the photo is not under- or overexposed.
  • You don't need flash cables. Because a video light burns continuously, you don't need flash cables to control the light at the moment you take a picture. If your video light is powerful enough, you can also do off-camera lighting with it, as in the photo at the top of the page. The light in the background and foreground is from a video light.
  • During night dives, your video light is also directly your dive light. (But bring a spare dive light too, as your battery will run down faster!)
  • A video lamp is also multifunctional. Maybe you like to alternate shooting video and photos. With a video light, though, you can take photos as well as video, with flash you can only shoot.