This is Part 8 of a 10 part Natural Light Photography Series.

*The histogram is a graph on your camera that visually represents the tones in your image.*

When you’re underwater, exposure can be tricky. Light behaves unpredictably, and the colors you see in the moment might not translate well into your photos. Enter the histogram—a tool that provides instant feedback on your image’s exposure and tonal balance. Mastering the histogram will not only improve your underwater photography but also save you from the heartbreak of discovering poorly exposed images after the dive.

What is a Histogram?

Photographing alligators in Florida presented a unique challenge due to the dark, shadowy areas of their habitat. The limited light resulted in many underexposed images, as reflected in my histogram here. 1/250, f/7.1, ISO 3200

A histogram is a graph on your camera that visually represents the tones in your image:

Left Side: Represents shadows and dark tones.
Right Side: Represents highlights and bright tones.
Middle: Represents midtones and everything in between.

By analyzing your histogram, you can assess whether your image is underexposed (too dark), overexposed (too bright), or perfectly balanced.

Why You Need the Histogram

While your camera’s LCD screen can give you a quick preview of your image, it’s not always accurate. Bright sunlight or underwater glare can make the screen misleading. The histogram, however, provides an objective view of your exposure, allowing you to adjust settings on the spot and avoid guesswork.

How to Use the Histogram Underwater

Check for Clipping:
- If the graph is pushed all the way to the left, you’re losing detail in the shadows.
- If it’s pushed all the way to the right, your highlights are blown out and lack detail.
Aim for Balance:
- A well-exposed image will have tones distributed across the histogram, with no harsh spikes at either end. Keep in mind that the ideal histogram varies depending on your subject and lighting conditions.

We had heavy cloud coverage that caused the light to scatter unpredictably. I photographed this sperm whale under these conditions—slightly underexposed but still well-balanced. The image had some highlights in the water from the sun breaking through the clouds. 1/320, f/9, ISO 320

4. Adjust in Real-Time:

If your histogram shows overexposure, increase your shutter speed, narrow your aperture, or lower your ISO.
For underexposure, do the opposite: decrease shutter speed, open your aperture, or raise your ISO.

Why the Histogram is Critical Underwater

Underwater conditions are dynamic—light can change in an instant due to depth, water clarity, or cloud cover. By checking your histogram regularly during a dive, you can adapt to these changes and ensure your images are consistently well-exposed.

Tips for Mastering the Histogram

At 30 feet deep with the great hammerheads off Bimini, the lighting was ideal, and my settings were dialed in perfectly. As a result, we captured a well-exposed image, which is reflected in my histogram. 1/320, f/10, ISO 400.

Practice on Land: Familiarize yourself with the histogram before heading underwater. Practice reading it in different lighting conditions to understand how your adjustments affect the graph.
Check Exposure Frequently: Make a habit of checking your histogram after each major adjustment to your camera settings.
Use RAW Format: Even with the best histogram practices, minor tweaks may be needed in post-processing. Shooting in RAW gives you more flexibility to adjust exposure and recover details.

Beyond Exposure: Evaluating Tonal Range

The histogram isn’t just about avoiding over- or underexposure—it’s also a tool for evaluating tonal range. A balanced histogram often results in an image with more depth and detail, capturing the full spectrum of light and shadow that makes your underwater subjects come alive.

Coming Next

In the next blog, we’ll discuss post-processing—a vital step in bringing your underwater images to life. Learn how to enhance colors, recover details, and make your photos truly pop. Stay tuned!

THIS IS PART 8 OF A 10 PART SERIES.

PART ONE - Is Natural Light Photography Photography For You?
PART TWO - The Euphotic Zone! Your best friend.
PART THREE - Custom White Balance, Natural Lights Secret Weapon.
PART FOUR - Shutter Speed: Freezing Moments Underwater.
PART FIVE - Aperture: Achieving Sharpness and Depth Underwater
PART SIX - ISO: Balancing Light Sensitivity Underwater
PART SEVEN - Focus Points: Keeping Your Subject Sharp Underwater
PART EIGHT - The Histogram: Your Underwater Photography Lifeline
PART NINE - Post-Processing: Bringing Your Underwater Images to Life.
PART TEN - The Freedom of Natural Light Photography: A Connection to the Wild

This is Part 3 of a 10 part Natural Light Photography Series.

*Thresher Shark off Malapascua Island, Phillipeans. Depth 70’* 1/250, f8, ISO 1250

When it comes to natural light photography underwater, no tool is more important than custom white balance. This technique allows you to compensate for the loss of color as you descend and is essential for capturing vibrant, true-to-life images. If you don’t master this skill, you’ll struggle to retain the natural beauty of the underwater world in your photos.

Why Custom White Balance Matters

Underwater, colors disappear quickly:

Reds vanish at around 15 feet.
Oranges at 30 feet.
Yellows at 60 feet.
By the time you’re at 100 feet, you’re left with muted greens and blues.

*Reef off Malapascua Island, Philippines. Depth 50 feet.* 1/160, f4.5, ISO 800

Custom white balance tells your camera what “white” should look like in your current conditions, helping it correctly interpret other colors. Without it, even the most perfectly composed shots will appear dull and washed out. While post-processing can help to some extent, getting it right in-camera is the best way to ensure your images look stunning.

How to Set Custom White Balance

Ignore Camera Presets:
Built-in white balance presets (e.g., “daylight” or “cloudy”) aren’t designed for underwater use and won’t give you accurate results. Go straight to custom white balance mode.
Find a Reference Object:
Snap a photo of something white or gray that’s lit by the same light you’ll be shooting in. This tells your camera what white should look like in those conditions. Common references include:
- White balance cards (designed for underwater use)
- The sand on the ocean floor (a favorite of mine)
- White fins, wetsuit trim, or dive slates
Recalibrate Often:
Light changes as you descend or ascend, so you’ll need to adjust your custom white balance every 10 to 20 feet to maintain accurate color representation.

*Great Hammerhead off Tiger Beach, Bahamas. Depth 40 feet.* 1/320, f8, ISO 250

What If You Don’t Have a White Balance Card?

Improvisation is key! Some options I’ve used include:

The bottom of a boat (if it’s white)
A diver’s tank (as a gray reference)
Propeller blades when swimming near the surface

Just be sure to communicate with your dive buddies beforehand if you plan to use their gear for calibration. No one wants to feel awkward when they catch you taking close-ups of their fins or tank!

*Schooling Jacks at Cabo Pulmo, MX. Depth 50 feet.* 1/320, f9, ISO 640

Tips for Success

Experiment Until You’re Happy: Don’t be afraid to adjust multiple times during a dive. Each dive site and condition is different, and the more you practice, the better you’ll become.
Pre-Set Your Camera Settings: Before setting white balance, make sure your shutter speed, aperture, and ISO are already dialed in for the conditions. This ensures a balanced exposure and gives you a better foundation to work with.
Use the Histogram: Check your histogram regularly to confirm proper exposure and avoid relying solely on the camera’s LCD screen, which can be misleading underwater.

The Freedom to Create

Once you’ve mastered custom white balance, you’ll unlock a new level of creative freedom in your photography. You’ll be able to produce vibrant images that capture the underwater world as you see it—full of life and color.

Coming Next

In the next blog, we’ll explore shutter speed and how to use it effectively to capture movement underwater. From slow-moving sharks to speedy dolphins, mastering your shutter speed is critical to creating sharp, dynamic images. Stay tuned!

THIS IS PART 3 OF A 10 PART SERIES.

PART ONE - Is Natural Light Photography Photography For You?
PART TWO - The Euphotic Zone! Your best friend.
PART THREE - Custom White Balance, Natural Lights Secret Weapon.
PART FOUR - Shutter Speed: Freezing Moments Underwater.
PART FIVE - Aperture: Achieving Sharpness and Depth Underwater
PART SIX - ISO: Balancing Light Sensitivity Underwater
PART SEVEN - Focus Points: Keeping Your Subject Sharp Underwater
PART EIGHT - The Histogram: Your Underwater Photography Lifeline
PART NINE - Post-Processing: Bringing Your Underwater Images to Life.
PART TEN - The Freedom of Natural Light Photography: A Connection to the Wild