Before the histogram, photography enthusiasts had to go through a lot more effort to get good exposures. But while the histogram is one of the most useful tools on your camera, it's also one of the least understood.
Understanding the histogram in photography and how it tracks your exposure is one of the key steps in learning how to become a better photographer. In this quick guide - and with a few handy cheat sheets - we'll show you exactly how to interpret your camera's histogram.
Judging whether you have taken a decent shot and a decent exposure is simple with a DSLR. As soon as you fire the shutter, a preview of your picture flashes up on the LCD.
You can instantly see if the shot is too bright, or too dark - so it seems unnecessary to have a second, more scientific, way of judging the suitability of your exposure settings… So why bother looking at the histogram?
First, and foremost, displaying the camera's histogram is not a replacement for looking at the image itself when you review a picture. This mathematical graph simply gives you some additional, but invaluable, information.
Reviewing images with your camera's histogram
The qualitative nature of the preview image means that it can be hard to see if an area of the shot is slightly too dark, or slightly too bright. The quantitative graph does not lie, and tells it to you straight.
Once you learn to read them, histograms clearly show the exposure - and whether you need to use exposure compensation to darken or lighten the next image you take.
In the first of our three histogram photography cheat sheets below we show you a typical histogram and explain how to read and assess the graph.
Simply click on the infographic to see the larger version of this histogram photography cheat sheet, or drag and drop it to your desktop.
Most importantly, your histogram also tells you about the contrast of the scene. This allows you to avoid - or at least take special care with - subjects that have a greater range of brightnesses than your sensor can cope with.
It also ensures that you get the best-quality results from your sensor when shooting low-contrast subjects.
The standard histogram - found on all DSLRs - plots the brightness (or luminosity, to use the scientific language) of every pixel in the picture.
This brightness is measured on a 256-step scale (the number of permutations available in a JPEG digital image). This graph can also be displayed as you frame up a picture on cameras that offer Live View (more on that later).
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