Taking Better Photographs
Using the Digital Histogram

Most digital cameras sold today allow you to view an image's histogram on the LCD screen. This is a very usefull tool for all photographers and if YOU are not using it, you are not taking the best pictures you can.

Have you ever seen professional photographers looking at the back of their cameras after taking a picture? They weren't looking at the image, they were checking the histogram to see if they "got the shot", or they had to make some adjustments and shoot again. Instant feedback! Isn't digital photography wonderful?

A histogram is a graph indicating the image's brightness. The bottom of the graph has 254 graduations, with pure black being on the left and pure white on the right. The height of the graph indicates the number of pixels in that particular brightness range.

The more pixels toward the left indicate a darker image. The more pixels to the right indicate a brighter image. If the graph is shifted to the left, some of the detail in the shadow areas may be lost. Where as, if the graph is shifted to the right, highlight detail may be lost. The tones between will be reproduced correctly. By viewing an image's histogram, You can see if the exposure and overall tonal quality are correct.

There is no right or wrong histogram. What you are looking for is a graph starting about 10 pixels from the left side and ending about 10 pixels from the right side and a nice even distribution of pixels through the rest of the graph. I know, you can't see 10 pixels on those small screens, but you get the idea. You just don't want the graph beginning or ending on the vertical end lines.

With an image that is too dark, or under exposed, you would set your exposure compensation using plus numbers. And if your image is too light, over exposed, you would use minus numbers.

If your camera has a manual mode where you can set exposure (f/stop) and shutter speed, you could use either one or both to correct your image. There is a relationship between aperture (f-stop) and shutter speed that will be covered when dealing with exposure.

Things to consider when making the decision on which adjustments to make have to do with depth of field and how steady your camera will be. If you do not want to change the depth of field, make your correction by slowing down the shutter speed. Be aware that with a slow shutter speed, you could move your camera while the shutter is open, the result being a blurred image.

A Good Rule to Follow

Never use a shutter speed that is slower than the focal length of your lens when hand-holding your camera. So what does that mean? Well, if you're using a 200mm lens, your shutter speed should NOT be slower than 1/200sec. If you have to use a slower shutter speed to get the shot, try to brace your camera on something stable or consider using a tripod.

If depth of field is not a consideration, then opening up the aperture (changing the f-stop from f8 to f5.6) would accomplish the same thing as decreasing the shutter speed one stop without the worry of a blurred image.

Always remember, "You are the Photographer" and you make the creative decisions. Sometimes you have to sacrafice some shadow or highlight detail to get the picture YOU want.

Return to Photo Tips

Return from Histogram to Home Page