Using The Histogram in Manual Mode :: Digital Photo Secrets

Using The Histogram in Manual Mode

by David Peterson 3 comments

Histogram. It's one of those words that makes you just want to switch your camera back to auto mode and forget everything you've ever learned about camera settings and exposure.

I get it. Histograms recall economics classes, or maybe statistics or other college math courses you'd really rather forget. It's that jagged, graph shape that looks about as unfriendly as your neighbor's doberman. Lots of beginning photographers like to pretend it doesn't exist, and who can blame them?


This is a good histogram, or one that indicates that this evenly-lit scene is well-exposed. There are some whites and some blacks, with most of the tones falling in the middle.
[ Top image Happy snowkitty by Flickr user Tambako the Jaguar]

Really, though, the histogram is quite a friendly little tool, however ferocious it may seem. In fact some people may even go so far as to call it the photographer's best friend, because once you understand it, it really is very simple to make use out of it. Learning to understand your histogram, in fact, is one of the big steps you can make towards improving your photographs and nailing exposure every single time.

What is a histogram?

Just in case I lost you, every photograph you take with a digital camera has a histogram associated with it. Most cameras will let you view this histogram right on the LCD screen, the moment you make the exposure. The histogram can look like a bell curve, but it is really a bar chart with a lot of different data points—all those different points help create a chart that can sometimes have a bell-curve shape or a much more jagged appearance. The shape of each individual histogram can tell you a lot about the exposure of your photograph.

In simple language, a histogram is a chart that shows you the tonal range of your image. When you look at a histogram, you're able to determine exactly how much white there is in your shot, how much black there is, and all those values in between. This is important, of course, because a good exposure needs to have a broad range of tones from black to white. A quick look at a histogram will tell you exactly whether or not you achieved this with your image, and if not which tones are deficient.
How a histogram can help you shoot in manual mode

When you shoot in manual mode, sometimes you feel a little bit like you're flying blind. After all, those auto-modes used to do all the thinking for you, leaving you free to think about things like composition and subject. That's why the histogram is such an important tool for getting your exposures right in manual mode.

How to read a histogram

Reading a histogram is really very simple. Black is on the left, white is on the right, and the midtones are in between. If you have a shot with a "good" histogram, then you'll have one with a few blacks, a few whites, and a good range of tones in between. This will often look like a bell curve, but it can also look jagged or wavy. What is important is that both blacks and whites are present on the chart, with most of the tones in that middle portion. A "bad" histogram, on the other hand, is going to be skewed—with a lot of tones falling on that left side (indicating underexposure, or loss of detail in the shadows) or on the right side (indicating overexposure, or loss of detail in the highlights). This is what photographers mean when they say "shadow clipping" or "highlight clipping." These two problems will be obvious when viewing a histogram, because the histogram will look like it has been cut off on one side.

How to interpret a histogram

Histograms are honest, but you need to know how to interpret them on a case-by-case basis. This histogram suggests clipping in the highlights, but because it's a high-key image that doesn't necessarily indicate a problem.
[ Top image Clusters by Flickr user Joel Olives]

Like so many other things in photography, the histogram is not a magic wand. It doesn't tell you everything, and the information it does give you can sometimes be misleading. What it does do is give you an honest representation of those tones—and it's up to you to interpret them based on the lighting situation. For example, if you're shooting a pretty evenly-lit scene but you're getting histograms that show highlight or shadow clipping, then the chances are very good that you've got a problem with your exposure. But what if, for example, you're shooting deliberately into the sun in order to create a silhouette? You may get clipping on both the shadow and highlight sides of your histogram, because that's the look you were trying to achieve with your image. You have a lot of detailess blacks because that's the definition of a silhouette. And you may also have blown out highlights, particularly if you've included the light source in your image.

This histogram suggests shadow clipping, but the image is deliberately low-key, so the black shadows were the photographer's creative choice.
[ Top image The world always looks brighter from behind a smile :-) by Flickr user Rakesh JV]

So the histogram doesn't know everything, and you'll need to really know your lighting situation and your goals for any one photograph before you can make the best use of it. In general, every-day lighting situations, though, the histogram can be invaluable. Get in the habit of checking it every time you take a photo—you can set your camera up to show you the histogram with each image as you take it or as you page through your shots on your camera's LCD. If you notice that you're getting clipping in the highlights or shadows, add some exposure compensation, then reshoot and recheck. That histogram is going to guide you to the perfect exposure for the situation that you find yourself in, and as a result you'll get consistently better shots.

Conclusion

Now that you know you aren't going to be graded on histograms by that math teacher you once had, you know, the one that used to be a drill sergeant before he decided to take a job as a statistics instructor—it's time to turn that function on on your camera and get used to seeing it there every time you release the shutter. When you're shooting in manual mode, this is going to help you judge how well your meter is doing in any given lighting situation. If your histograms are on the dark side or the light side, you know you have to make adjustments to your exposure.

Just spend a second or two paying attention to that little chart and you'll develop a good feel for how the histogram can digitally explain to you what is happening with the tones in your photographs. Once you learn how to apply this information to your photography, then the histogram will stop being that stern college professor and it really will become your friend.

Comments

  1. Janis Goonan says:

    Thank you so much for explaining the Histogram David! I finally know what on earth I'm looking at and why. This is a lot easier than Algebra and I will use this information daily... unlike all the math classes I took years ago!

  2. Norma Irving says:

    Thanks for explaining that in an understandable way David. I am learning so much more from doing this course, having the challenges forces you to understand the emails you have been sending me over the last 12 months.

  3. Diane Bell says:

    Great article. I actually did have a math teacher who used to be a drill sergeant.

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Difficulty:
Beginner
Length:
9 minutes
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