Histograms | The new way to get the exposure right

A histogram is a graphical display of the distribution of tonal values in the image, from the darkest (on the left) to the lightest (on the right). The shape of the histogram can tell you a lot about the image’s characteristics and, indeed, its flaws. If the histogram is ‘clipped’ (cut off abruptly) at either end, this means the photo has missing shadow or highlight detail.

You can use your camera's histogram display, where available, to get the exposure right rather than relying on traditional metering techniques.

There are three places where you'll find histograms:

1. On the camera's LCD when you're composing the shot. Many compact cameras can display a histogram during shooting, and it's worth checking the manual to find out if yours does. Digital SLRs with a live view mode will be able to display a histogram too. You can use the histogram in conjunction with the EV compensation control to get the exposure exactly right.

2. All digital SLRs and some compacts can display a histogram in playback mode too. On digital SLRs which don't have a live view mode, this is your chance to check the exposure. If you need to, you can then adjust the camera's exposure controls and re-shoot.

3. Image-editing programs display histograms too, usually in the Levels dialog (e.g. Photoshop and Elements). The histogram can help diagnose any exposure problems so that you can see what you need to do to fix them. If highlight or shadow detail has been 'clipped', though, it's too late to do anything about it on the computer. You really do have to get the exposure right with the camera.