Exposure & Your Histogram

Proper photo exposure is a fundamental of underwater photography.

Today most photographers are using powerful editing software, and as a result, many of us are not focusing as carefully on capturing perfect exposure in-camera. More and more, we’re thinking, “that’s ok, I’ll fix it in Lightroom.”

This is not good!

Lightroom and other editing software is incredibly powerful, yet even when shooting in RAW file format there is still a limit to the global adjustments you can make before there is a noticeable decline in image quality.

With these limits in mind, would you rather spend your ‘editing allowance’ on correcting exposure or in adjusting colors and contrasts to take a great image into a fantastic image?

The decision should be simple. The better the image you capture in-camera, the more you can use editing to enhance the image instead of save it, and the better your final result.

Let’s learn how to use the histogram to ensure you capture proper exposure in your underwater photos every single time.


Master Exposure with the Histogram

What is the Histogram?

The histogram is a visual display of the photo’s exposure data. This data is presented as a graph with the black point on the left and the white point on the right. All the exposure data between these points is takes on a curve that changes shape based on how bright and dark the various portions of the composition are. This representation of light and dark as a chart makes the histogram a great tool for measuring photo exposure.

You can find the photo’s histogram when reviewing your images in-camera or inside of your editing software when post-processing.

The same image represented by three different histograms based on 1-stop exposure adjustments.

How does the Histogram help to capture correct exposure?

A properly exposed photograph will deliver a histogram with a curve shape within the black and white point boundaries. This area is known as the exposure of the image. Ansel Adams created a zone system for photo prints, but today we can look towards Adobe, who defines the exposures zones as follows: Blacks, Shadows, Primary Exposure, Highlights, Whites.

Exposure is tricky to gauge underwater since our LCD screen is so bright and the ambient light is relatively dark. As a result, we see our LCD and think we’ve got a properly exposed image, then load it onto the computer and realize the image is underexposed.

This histogram is based off of true exposure data… and data never lies.

This is why the histogram is so important for measuring exposure underwater.

Beyond that, you can also use the histogram while editing and fine-tuning your images

As underwater photographers, we should constantly be checking the histogram to ensure our images are properly exposed. I check my histogram after composing and lighting every new composition.

Does my camera have a Histogram?

Absolutely! All cameras have a histogram. To find it, make sure you have some images on your memory card in the camera. Next, press the Info or Display button one to two times to toggle through the review displays. One of these will show the histogram and/or image. Voila!

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Brent Durand

Professional writer and underwater photo instructor. Brent is an avid diver and surfer, and has led many intensive photo workshops around the world. BrentDurand.com.