You’ve likely scrolled right past the histogram screen, perhaps even displaying it accidentally while looking for another setting. At first glance it appears daunting, even mathematical. It’s tempting to just avoid it altogether, but the question still lingers, “what does this odd graph mean?” In this tutorial, I’ll detail exactly how to make this feature work to your advantage. Once the potential benefits of this tool are realized, you’ll wonder how you ever got by without it.
Think of the histogram as a visual cheat sheet for photographing bright tones. To render a subject as true white, you want the data on the right-hand side to be as close to the edge as possible. This will indicate a crisp exposure rather than a muddy, grey appearance. As you change the exposure to let in more light, the histogram will inch towards the right. Keep adjusting your settings until it’s literally just a hair from the outer wall. You are now maximizing all of the wonderful dynamic range your camera is capable of.
Once the data actually collides with the right hand wall of the histogram, you’ve technically overexposed part of your scene. This means there is no detail in your highlights, but rather a hotspot that is impossible to recover even with sophisticated software. While this data is valuable, it doesn’t tell you exactly where the trouble spot is in your scene. This is where the “highlight alert” becomes a helpful aid.
Commonly referred to as “the blinkies,” this feature alerts you to the precise location that’s overexposed. If it’s the actual sun in a sunset photo, I don’t worry about it. If however, it’s the sky, or part of the landscape, it’s best to adjust the exposure and reshoot before verifying that you’ve resolved the issue. This often involves bracketing a few exposures so you have more options once back in the digital darkroom.
There’s a misconception amongst many photographers who believe a histogram that’s stacked to the left is automatically a bad exposure. Actually, it’s simply an indication that dark tones exist in the scene. This spiderweb for example, was in the sunlight with a shadowy background. The data on the left means it is inky black. Had the histogram data been more centered, the area behind the spider’s web would be grey.
When you are shooting on bright sunny days, it’s very difficult to judge an exposure purely based on the LCD screen. The histogram eliminates the guesswork and gives you a quick data-based look at the exposure. For this flower, I wanted to create a moody scene and opted to underexpose and keep more of the data to the left.
As you can see, the left- and right-hand wall are very important considerations. The space in the middle is also valuable however, essentially offering a glimpse at the medium-toned parts of your exposure. For example, a field of properly exposed green grass would fall in the center of the histogram, and so would a medium-blue sky. How prevalent these tones are in your shot will dictate the height of the data on the graph. The greater the area of medium tones, the higher the data will stack.
By using these tools you can routinely create predictable results in any situation. These underused features give you the ability to take control of your camera and get the shot right at the time of the exposure. As a benefit, that means less time in the digital darkroom “fixing” problems that could have been prevented. Now that you have the knowledge, you will no longer fear the histogram, but use it to your advantage.