How to read a histogram and stop guessing exposure
The camera screen lies, especially in bright sun. The histogram does not. Learn to read it and avoid blown highlights and blocked shadows.
The image on your camera’s screen depends on screen brightness and the light around you. In Yucatán’s midday sun, almost every photo looks dark on the back of the camera. The histogram is an objective graph of your exposure that you can trust anywhere.
What the graph shows
The horizontal axis goes from pure black on the left to pure white on the right. The height at each point shows how many pixels have that brightness. There is no single correct shape; a night scene leans left and a snowy or white-sand scene leans right.
The two warnings
- Data piled against the right edge means clipped highlights: pure white with no detail, which cannot be recovered.
- Data piled against the left edge means crushed shadows: pure black with little detail and lots of noise if brightened.
Expose to the right, carefully
For RAW files, a slightly bright exposure that stops just short of the right edge keeps the most detail and the least noise. Pull it down in editing. Turn on zebras or highlight warnings to see exactly where clipping happens.
Use it in the field
Enable the live histogram in the viewfinder on your Sony camera. Glance at it before each new scene, especially when the light changes, such as moving from a shaded courtyard to a sunny street.
