Introduction:
One of the most important features of the modern digital camera is the image display and the histogram. Understanding what information that it is giving you and how to use it will help you to get the correct exposure and prevent details from being blown out of the image.
- Black Scale 0-256 or 8 Bits
Discussion:
Every image has so many dark or black pixels (shadows) and midtones, and high lights in it. Bright images will have more highlights and the histogram with be pronounced to the right side. You must not exceed the right side during your exposure or you will loose information.
- Daylight Landscape image properly exposed to the right side with Canon
Canon cameras are best exposed just into the 5th quadrant for normal daylight type pictures. This histogram shows the distribution of the darks, midtones and highlights in the image. The darks are on the left side, the midtones in the middle and the highlights on the right side.
Notice that no peaks exceed the chart. That would result in blowing out the information for those pixels.
You may have heard of color charts used to set the exposure and to calibrate the camera. For critical shoots, it is always recommended to shoot a color chart. How ever for casual and wedding shots, this is normally not practical. Under these conditions, shooting a grey object will normally suffice. Let us look at the histogram of a color chart.
- Histogram of a portable color chart
The color chart that I normally use is a full 8x11 inches and will give a different histogram than the above example. You can see from this example, the large amount of dark areas show on the left side of the image. The white or bright highlights are peaking to the top of the histogram. It is important to have your camera set to blink or flash to show you if any areas exceed the exposure.
- Here the image is over exposed to the right resulting in detail blow out
- You should look at all of the Color Channels -Red - Green - Blue of an image
- Not all images will have highlights Some will properly expose to the left
Masters-Tip: Look at the subject matter being photographed to determine if the histogram appears to be correct. Always change your exposure if blowouts are seen. Use the blinkies and look at the image. Canon calls this the Highlight Alert. You may NOT be able to stop blowout in bright or dark areas of the photograph while maintaining proper exposure.
Summary:
The histogram shows the distribution of your images dark to white tones.
- Summary of tonal distribution
Masters-Tip: Turn on your camera`s Highlight Alert warnings referred to as the "blinkies".
Masters-Tip: Always check all of the cameras histogram channels.
Masters-Tip: Always shoot a 18% grey body which can help in Post. We carry a small lens cleaner that is 18% grey and can easily be put on one shot and removed.
Masters-Tip: Slightly underexposed images can always be brought back in Post Processing while maintaining the image details. This is the secret of HDR.
Hope that you enjoyed today's post. Have a great day! Thanks for dropping by.
Kirk is a Professional Wedding Photographer in Windsor Ontario Canada. In appreciation if you would be so kind as to give a G+ and a Facebook Like KW Masters Photography on his Facebook page. You only have to do this once and add your likes and G+ per post.
Well explained - thanks!
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