| Understanding Exposure Part 2 | |
| "Correct" exposure of a subject with a wide range of tones. | |
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The image above contains a wide range of tones running from the shadows of the black hat through to the patch of bright sky. The Histogram shows a "correct" exposure with values right across the scale.
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If this shot had been underexposed the histogram would show the values bunched up to the left. Overexposure would cause the values to be all over to the right. Histograms are the best way to assess the accuracy of an exposure because they represent the exposure in a graphical form that is unaffected by viewing conditions. |
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If your monitor is correctly adjusted you should see 16 distinct tones in this Greyscale. |
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If a number of the dark tones merge in to black or the light tones merge to white your monitor needs to be adjusted. Remember, if your display is not calibrated you are not seeing your photos as they really are. |
However not all histograms look alike and you need to learn how to interpret them. What happens when the subject does not have a full range of tones running from black, through shadows, midtones, highlights and all the way to white?
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| "Correct" exposure of a High-Key subject. | |||||||||
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| The High-Key subject of this photograph does not include any dark areas. Even the soft shadows are no darker than a midtone, consequently the histogram only shows values on the right. In this case it does not mean that the image is overexposed. |  |
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| "Correct" exposure of a Low-Key subject. | |||||||||
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| Here we have a Low-Key subject that is made up of dark tones. The histogram reflects this fact. Note that this shape of histogram would indicate underexposure in a subject with a full range tones. However here it shows "correct" exposure. |  |
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OK now we know what a good exposure should look like and we know how to objectively assess it for accuracy using the histogram. |
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