Unveiling the Power of Histograms in Data Analysis

Using a histogram is a powerful way to assess exposure in your photos and ensure you’re capturing all the important details in a scene. If you have a built-in histogram on your camera, a quick glance can tell you a lot about the quality of your image.

Understanding the Histogram

What is a Histogram? A histogram is a graphical representation of the tonal range in your photo. It displays the distribution of light, from dark shadows (left) to bright highlights (right).

Key Zones on the Histogram:

• Left: Shadows and blacks.

• Middle: Midtones (neutral tones).

• Right: Highlights and whites.

  
  

If you use Lightroom CC you'll find the histogram in the top right corner

Your camera probably has a built-in histogram and it's an invaluable reference for adjusting settings. I use the info button on my OM-1 to toggle tools on and off.

Essentially, a histogram is like a map for your image’s brightness and contrast, ensuring you make informed decisions rather than just relying on how the image looks on your screen.

I've been caught out in the past as screens adjust due to the level of brightness, so they are not a true indicator of what you are capturing. Getting into the habit of checking your histogram is a quick and easy way to get exposure optimised without guesswork!

Steps to Use the Histogram for Correct Exposure

Check for Clipping

• Shadow Clipping: If the graph is bunched up against the left edge, you're losing detail in the shadows (pure black areas).

• Highlight Clipping: If it’s pushed against the right edge, you're losing detail in the highlights (pure white areas).

Solution: Adjust exposure to bring these areas back within the histogram’s range unless intentional (e.g., silhouetted subjects or high-key images). You may need to shoot with a 'happy medium' and adjust in post processing if the light is harsh or there is very light or dark areas in your composition.

Aim for a Balanced Histogram

• A balanced histogram generally has most data within the middle without significant clipping on either end.

• The shape of the histogram depends on the scene. A high-key image (bright) will naturally lean right, while a low-key image (dark) will lean left.

  
  

Expose for Important Details

Determine which parts of the image are most critical. For example:

• In wildlife photography, ensure the subject (e.g., a bird’s feathers) isn’t overexposed or lost in shadows. Pay attention to white and black feathers in particular.

• Use Exposure Compensation to adjust if you don't have live view (see below).

Use Live View or EVF Histogram

Many modern cameras allow you to view the histogram in real time. Use this feature to adjust settings (shutter speed, aperture, ISO) before taking the shot.

ETTR (Expose to the Right) Technique

As with most photography guidance floating around on the internet, some swear by this technique and for others it's a strict no go! My advice - try it and see if it works for you.

HOW-TO: Push the histogram slightly toward the highlights without clipping. This minimises noise in shadows and ensures maximum detail. Be cautious not to overdo it, especially in high-contrast scenes.

Adjust with Post-Processing in Mind

While histograms help with in-camera exposure, unless you're shooting in perfect light you can successfully recover some highlights or shadows during post-processing if you shoot in RAW - and using the histogram in your editing suite can offer further insights into where you need correction.