Take Better Pictures – Lesson 5 Histogram
The Histogram is your friend
In this lesson you will start learning about exposure, and how to interpret the histogram.
The graph above illustrates the tones in a photo. The left side represents the dark areas of your photo, the shadows. The right side represents the bright areas, the highlights. The middle section represents the mid-tones.
After you take a picture you typically look at it on the back of your camera. You can’t really tell from the image playback screen if your photo is exposed properly. The brightness varies on them so much, and they also look different if you are indoors or outside in the bright sun. So to really know if your photo is exposed properly, check your histogram. It shows you whether a photo is too dark or too light.
Here is an examples of what the histogram looks like on the back of your camera. You can also see a lot of other information. You should recognize some of these things now: ISO, WB, File Size and File quality.
If you don’t know how to find the histogram, try pressing the info or display button when in image playback mode. This works on most cameras. If you can’t find the histogram, time to crack open the camera manual and look up image playback and find out how to display the histogram.
If you shoot in jpg mode, it is really important that your exposure is correct. If you overexpose your photo and lose highlight detail, you can never get it back. If your image is too dark, you can make it brighter in Photoshop, but it won’t be the best result.
Too dark, too light, just right
Normal exposure – histogram goes all the way across, but doesn’t climb the walls
Over exposed photo – too bright – Histogram climbs up the right side of the graph
Under exposed photo – too dark – Histogram climbs up the left side of the graph
Your homework this week:
Every time you take a photo, check your histogram. If it is over exposed, reduce your exposure by taking light away. If it is under exposed, add light. Use the +/- function on your camera to do this.
Extra tips for this lesson
How to fix a bad histogram
If there is too much light, you need to take some away. If there is not enough, you need to add some. The great thing about digital photography is that you can immediately re-take your photo if it’s not the way you want.
Back in picture taking mode, add or remove light to adjust your exposure. Look for the +/- button on your camera. When you press it a scale comes up. This may require another quick look at the owner’s manual to find this button and to see the scale. Look up Exposure Compensation in the index.
Do you ever see blinking areas when you play back your photos? They represent areas of your photo that are over exposed. You need to decide if those areas are important or not. If there are blinkies on someone’s head or nose, you might want to adjust your exposure. Sometimes you will get blinkies from shiny chrome, beach scenes and sunsets that just won’t go away no matter how much light you subtract.
If you photograph food, you might notice them in shiny pots and cutlery. In those cases you will have to live with it. Even the best digital camera sensors (and film) cannot capture detail in specular highlights.
Keep in mind that your histogram will also display an over exposed spike on the highlight side of the graph when you have specular highlights. Here’s a blog post that goes into a more detail about interpreting histograms.
Next lesson: Seeing light
Previous lesson: White Balance