Let’s talk about lighting and background handling in underwater macro photography. First, let’s discuss why artificial lighting is necessary underwater.
During the deep diving segment of the AOW (Advanced Open Water) course, the instructor typically brings a color chart underwater. As we descend to different depths, we observe how the colors on the chart gradually fade—until eventually, only shades of blue remain. Why does this happen?
We all know that sunlight is composed of seven colors: red, orange, yellow, green, cyan, blue, and violet. Each of these colors has a different wavelength, and when sunlight enters the water, each wavelength is absorbed at a different depth:
The depth at which different wavelengths of light are absorbed by water varies significantly.
As shown in the diagram, sunlight's red wavelengths are almost entirely absorbed by just 5 meters deep. As depth increases, more colors are progressively filtered out—until around 30 meters, where only blue light remains. This explains why underwater photos taken without artificial lighting appear overwhelmingly blue, as demonstrated in the following set of comparison images:
Natural light photography
Strobe-lit
As seen in these two comparison photos, images taken with natural light appear completely blue-toned, while using strobes allows the white underside of the manta to be accurately reproduced. The primary purpose of artificial lighting underwater is color restoration.
Light Source Options
Generally, there are two types of artificial lighting used in underwater photography: continuous lighting and strobes. Continuous lighting can be further divided into:
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Focused beam (e.g., focusing dive torches)
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Diffused light (e.g., video lights)
Focused-beam flashlights are mostly used in macro photography. Their advantage lies in the small beam angle, making them easy to control and particularly suitable for use with compact cameras.
Their disadvantage is precisely due to this small beam angle - they are only suitable for macro photography, have certain limitations in lighting flexibility, and aren't well-suited for shooting fast-moving subjects (this doesn't apply if you have a light holder).
The focused-beam flashlight produces its strongest light in the center, but there's usually a halo around it. In some cases, this halo can affect the final image quality.
Beam angle of the beam flashlight
Video Lights feature a wider beam angle with more even light distribution, making them versatile for various applications. However, due to their diffused light nature, they offer weaker penetration compared to focus beam torches - providing broader coverage but over shorter distances.
Video light beam angle
How to Reduce Backscatter in Underwater Photos
First, let's address a common issue. Many beginners notice their photos are full of white specks when first using underwater lights. Where do these white dots come from?
In reality, the water is filled with suspended particles. When we shine a light underwater, these particles become clearly visible. The white specks in photos are actually light reflections from these suspended particles entering our camera lens.
How to Capture Black Background Photos
Let me demonstrate this with practical examples. First, let me show you my simulation setup:
Here's a photo I took in normal room lighting conditions using my camera (D850 + 60mm lens) in auto mode:
This lighting environment is similar to natural underwater conditions. The camera's auto mode calculated these exposure settings: F3.3, 1/60s, ISO1000.
In underwater macro photography, we typically:
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Use smaller apertures for greater depth of field to capture more creature details
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Choose faster shutter speeds to avoid motion blur
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Keep ISO as low as possible for better image quality
Now, using my standard underwater macro settings (F22, 1/200s, ISO100) in the same environment, the result looks like this:
No doubt about it - what you're seeing is a completely black photo. This clearly demonstrates that under these lighting conditions, using these camera settings results in severe underexposure, making everything invisible.
This is precisely when artificial lighting comes into play.
Actually, I prefer to think of it this way:
It's not about making the background black - it's about choosing which elements we want to appear in our photo, and then illuminating just those areas with our lights.
For example, if we only want our photo to show the Costasiella kuroshimae (sheep sea slug), we position our lights to illuminate just that subject. Observe this lighting setup:
As you can see, I've carefully adjusted the angles of both strobes so that just the outer edge of their beams grazes the body of the Costasiella kuroshimae. The illuminated area is precisely controlled to cover only:
There are two crucial details here:
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My lighting deliberately avoids illuminating the wall behind the sea slug, causing the background to remain completely black in the final image;
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The light only illuminates the water column between the lens and subject (about 10cm). In actual underwater shooting, many subjects are much smaller than this sea slug, requiring even closer shooting distances. This means the illuminated water volume contains negligible suspended particles, effectively eliminating backscatter in our photos.
The real-world shooting results demonstrate this technique:
Porcelain Crab (F20 1/200 ISO100)
Now, when shooting larger subjects or fish where we can't get close enough - leaving more distance between the camera and subject - if we still use the traditional two-strobe cross lighting technique, it would illuminate too large a volume of water. The result? A photo full of backscatter.
In these cases, we need to:
With the open water background, we carefully position both strobes so their inner edge lights just graze the sea slug's body while avoiding the water column between camera and subject. Using the same parameters as before (F22, 1/200s, ISO100), the resulting image achieves this effect:
In actual shooting conditions, light attenuates dramatically in water. Even at maximum strobe power output, the effective lighting range remains within 2 meters. Therefore, when shooting against open water backgrounds:
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The background water's reflected light remains insufficient to affect exposure, maintaining pure black backgrounds
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Due to rapid light falloff, suspended particles in background water receive inadequate illumination to appear in the final image
The real-world shooting results demonstrate this principle:
Lionfish (F22 1/200 ISO100)
Of course, the easiest way to shoot a black background is to use a snoot or a snoot. The light angle is very small and just covers the subject. You can use a top light or a diagonal top light to directly illuminate the subject:
Shrimp-goby symbiosis (F25 1/200 ISO100)
Several key points for shooting black background:
1. Adjust the camera parameters to make the natural light environment in a serious underexposure state;
2. Control the light to only illuminate the subject;
3. Lighten the sea water as little as possible.
4. Use edge light
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How to shoot color background
Some people like photos with rich colors and think that the black background is too monotonous. In addition, in actual shooting, there are indeed some terrains that cannot shoot black backgrounds. Then I will talk about how to shoot color backgrounds.
The difficulty of shooting color backgrounds lies in how to choose the background. The background must be beautiful and not conflict with the subject. The background cannot grab the attention of the subject, but the background must serve as a foil for the subject. This is actually not related to technology, but to personal aesthetics.
In shooting color backgrounds, the technology is related to the application of depth of field. I will continue to use actual demonstrations to explain. This time the simulated environment is like this:
Since the color of the wall at home is not bright enough, I invited the God of Wealth in my house to act as a temporary background. Since we need to brighten the background this time to restore the background color, we use a flat push light position:
Again, the rim light sweeps across the sea hare, avoiding highlighting the space between the sea hare and the lens, reducing noise. At this time, if we continue to use the above set of parameters (F22, 1/200, ISO100), the shooting effect is as follows:
You can see that the word "源" (source) and "广" (wide) in "财源广进" (wealth and prosperity) are clearly visible and very eye-catching. The background is colored, but this background is a minus for this photo. At this time, we adjust the shooting parameters: F4, 1/200, ISO100, and the effect is as follows:
The same lighting position, the same angle, the effects presented by the two shooting parameters are completely different. This is the application of depth of field, which is what we usually call a large aperture. The larger the aperture, the smaller the depth of field, and the higher the degree of background blur. The details of the blurred background are gone, leaving only the color, and the reflection of some bright spots presents a dreamy effect under the blurred effect. Such a background can play the role of setting off the subject.
The same is true in actual shooting. When we find a piece of beautiful coral and want to use it as a photo background, we will choose to use a large aperture to blur the background so that the background does not steal the subject itself, so that the attention of the person viewing the photo is still on the subject. The background plays a decorative role, and the content of the photo is richer.
Sea slugs (F8 1/160 ISO100)
There are a few points to note when shooting with a large aperture:
1. The aperture is large and the depth of field is shallow, but it cannot be so large that the details of the subject are lost too seriously. You must strike a balance between the degree of background blur and the loss of subject details;
2. The large aperture has a large amount of instantaneous light intake, and the output of the light should be appropriately lowered to avoid overexposure;
3. Still the same, use edge light to brighten the sea water as little as possible
In fact, the treatment of the background depends on your expression of the photo and the conditions of the shooting environment. There is no fixed rule. In the previous article, I said that I personally recommend that novices start shooting with black backgrounds when they first start shooting, because when shooting with a black background, you only need to focus on the subject itself, without distracting your attention to consider how to deal with the background, and do subtraction first. On the other hand, since black backgrounds usually use small apertures and have a large depth of field, there is a certain margin of error when you are not familiar with focusing at the beginning of shooting. Shooting with a large aperture requires your focus to be very precise. After the basic skills are solid, we can do addition, so that it is a gradual process.
I suggest that you can make a training plan for yourself:
1. Use a trip to practice focusing and master the focus distance and focal plane control of your camera;
2. Use a trip to practice shooting with a black background, familiarize yourself with the light angle of your lamp, the balance between power output and various camera parameters;
3. Use a trip to practice shooting with a large aperture, master the control of depth of field, and the balance between background blur and subject details.
After 3-4 trips of such targeted training, I believe you can take good photos. The subsequent improvement depends on your own experience accumulation and absorbing the advantages of other excellent photographers.
Well, this is the end of the underwater macro chapter
