Top Ten Tips for Nice Underwater Bokeh

One of the most frequent questions I hear from new photographers is “how do I get blurry backgrounds in my photos?” Bokeh, the Japanese word for fuzzy or blurry, describes the quality of the blur in the out-of-focus area in an image. To get a nice blurry background is to have nice “bokeh.” 

Getting nice bokeh can be hard enough as it is above water. Getting good bokeh underwater can be even more challenging when considering factors such as backscatter, artificial lighting, moving subjects, and complex substrate/backgrounds. 

Many underwater photographers, especially macro photographers, use bokeh regularly to accentuate different aspects of their subjects. Bokeh is useful for pointing the viewer to the “best” part of the image, creating a dramatic effect, and/or obscuring an unsightly background. Here are ten tips for getting nice underwater bokeh:

1. Open your aperture

An open aperture on your lens increases the amount of light hitting your sensor and decreases the depth of field (amount of in-focus area)* in your image. Therefore, increasing your aperture brightens your image and creates a blurrier background. To do this, shoot at a smaller f-number (e.g., f/2.8, f/5.6, f/6.3). 

*Click here for a description of Depth of Field

2. Get Close

Distance to a subject directly affects the depth of field. The closer you get to a subject, the shallower the depth of field, and a greater part of the image will be out of focus. This roughly translates to better bokeh.

3. Keep the most important part of your image in focus

In images with a lot of bokeh, the viewers eyes gravitate to the in-focus part of the image. This means the most important parts of an image, such as the eyes, face, rhinophores, etc., should be in focus. One of the first rules of shooting portraits is keeping the eyes in focus. This even more true for photos with a small depth of field. To do this, you can move your autofocus point so that it is over the area of the subject you want in focus. You can also lock-in your autofocus to the point you want in focus, and re-adjust your composition before taking the shot. Some photographers like to switch to manual focus and pan in and out with their camera until the correct part of the image is in focus. 

This image of a blue banded goby by Helen Brierley won Bluewater Photo's SoCal Shootout 2017 best of show. IT keeps the important parts of the image in focus - the goby's eyes and yawning mouth. Helen used the Nikon D500 with the Nauticam D500 Housing, flash trigger, Nikon 105mm VR lens, two YS-D1 strobes and the Subsee +5 diopter. Her settings were 1/200th, F18, ISO 200. Check out the story behind the shot.

4. Be wary of your background

Backgrounds are especially important to consider when shooting an image with a lot of bokeh. A wide aperture has a twofold effect on the background of an image. 

1. It becomes harder to isolate the subject with a black background 

2. It becomes easier to isolate your subject using a shallow depth-of-field

When shooting with a wide aperture, you should be wary of how background textures and colors affect your image. How complex is you background? Do your background’s color schemes match or complement your subject? What kind of bokeh are you trying to get – spots, polygons, swirls? Are you trying to get bokeh in the background or foreground?  

5. Get artistic with your lighting

Underwater photographers who shoot with wide apertures for the first time often struggle with their lighting. A wide aperture lets in a lot of ambient light and makes it harder to get good colors with your strobes. It’s important to mix ambient and artificial light to create a seamless color scheme that isn’t blue or washed out. There are a few ways to do this:

1. Bump up your shutter speed. Shooting with a quick shutter speed and wide aperture lets you get more artificial strobe light in the image but a smaller depth of field for good bokeh. 

2. Use a snoot – a snoot is a bundle of fiber optic cables that directs the light from your strobe to a smaller tipped end of the snoot, producing a tiny circle of light. This small circle of light can be used to illuminate your subject and help create contrast in your background, particularly in the form of a “black background image.” Too much of a black background can eliminate your bokeh. But mixing the black background with available bokeh produces an intriguing image. 

3. If you're shooting close focus wide angle with a shallow depth of field (open aperture) - get your strobes as close to the subject as possible without blowing out the image and creating backscatter. Reduce the power on the strobes to make sure they don't blow out the image.

6. Accentuate a pattern

As I mentioned before, bokeh helps define which part of the image is “important” by leaving important parts of an image in-focus. It can be especially hard to differentiate an important section of a pattern-type image. Bokeh makes it a little easier to appreciate a pattern in an image by artificially highlighting different sections of the pattern.

Take the image below, for instance. With a large depth of field, this would just be an image of tentacles. With a shallow depth of field, your brain first processes the in-focus tentacles and then sees the out of focus tentacles. The image leaves you imagining how the reality must look. It’s an image that makes you think.

7. Use a motion blur to produce bokeh

A wide aperture isn’t the only way to produce bokeh. Motion blur can have a similar affect on depth of field with a little more flexibility in the motion of the bokeh. To get a nice motion blurred bokeh underwater, lower the shutter speed (think 1/8th of a second or slower) and compensate for the influx of light by increasing the f-stop (close the aperture). Turn off your image stabilization and keep your strobes on. When you press the shutter, pan the camera steadily in the direction that you wish the blur to follow. The strobe will “flash freeze” the in-focus subject in place and the slow shutter will allow for the background to blur and blend together in a singular direction. 

8. Shoot wide (close-focus wide-angle)

Although popular with macro photographers, bokeh is a quality of all photos. And it’s widely ignored by wide angle photographers (pun intended). However, a good bokeh can be essential when shooting close-focus wide-angle. In order to do this, open the aperture and get close to your subject. Lighting can be difficult, so make sure your strobes are close enough to the camera without producing backscatter. The resulting image will highlight your subject and isolate it from the background. 

9. Bigger is better: shoot a camera with a larger sensor, and a lens with a larger focal length

There are plenty of benefits to shooting with a larger sensor – good bokeh is one of them. Cameras with larger sensors shoot with a shallower depth of field compared to cameras with smaller sensors (equivalent focal lengths and f-numbers). This means that full frame cameras will produce a better bokeh than cropped sensor, four-thirds, or compact cameras. Compact cameras are the most difficult to produce a good bokeh.

A larger focal length will also produce a shallower depth of field. So, shooting a zoom/macro lens (e.g., 105mm) will have a shallower depth of field than shooting with a fisheye (e.g., 8mm).

10. Get Creative! 

Post-processing has opened up a whole new world of bokeh effects. Although it would take another article to go over types of synthetic bokeh, check out our photoshop lesson on Gaussian blur. But synthetic bokeh isn’t found only in the realm of computers. You can also produce your own DIY bokeh with a nail polish and a slate!

* A shallower depth of field roughly equivocal to better bokeh. Depth of field is defined as the distance between the closest and farthest points in an image that are in focus. It helps to know the math behind Depth of Field:

Depth of field ≈(2u²NC)/f² 

C = circle of confusion

f = focal length of the lens

N = f-number

U = distance

As you can see, a shallow depth of field means decreasing the distance to the subject (u), opening the aperture (N), and increasing the focal length of the lens you shoot (f). For more information on depth of field check out our article explaining aperture, f-stops, and depth of field underwater.

Further Reading about Bokeh:

• How to Achieve a Good Bokeh Effect

• Macro Methods: Sharp Eyes and Nice Bokeh

• Creative DIY Bokeh

• Underwater Photoshop Lesson - Gaussian Blur