Reading the histogram

Learn how the graph on your camera can help you achieve better exposures

Being able to know what the histogram is telling you is one of the fundamental skills of digital photography. This small graph, which can be viewed alongside pictures you’ve taken, or in real time when your camera is set to Live View mode, is a visual guide to the exposure in frame. It’s better than trying to judge the exposure by looking at the image on the back of the camera, as the brightness of the screen influences the brightness of the image.

The histogram is a bar graph, with each bar showing how many pixels have registered each level of brightness – from black on the left, to white on the right. The bars are tightly packed, which gives the histogram its shape. There’s not a perfect histogram, as its shape alters according to what’s being photographed and the camera settings used to capture it.

Bright or pale scenes should see the histogram positioned towards the right side, while subjects that are dark overall should show a histogram closer to left side. The majority of scenes, however, are a mixture of shadows, mid-tones and highlights, and are likely to produce a histogram that fluctuates across the graph.

If there is an ideal histogram, it would be humped in the centre and taper off before it reaches the edges of the graph. You will, however, be faced by situations where the histogram doesn’t fit neatly into the graph – you’ll need to fine-tune the exposure or take steps to reduce the contrast between the dark areas and bright areas so you can capture more detail.