Using The Viewfinder - Canon Leather Soft Case 70 Advanced User's Manual

Histogram Function
The histogram is a graph that allows you to check the brightness
of the image. The greater the bias toward the left in the graph, the
darker the image.
The greater the bias toward the right, the brighter the image. If the
image is too dark, adjust the exposure compensation to a positive
value. Similarly, adjust the exposure compensation to a negative
value if the image is too bright (p. 52).

Using the Viewfinder

The viewfinder (Basic Guide p. 1) can be used to conserve power
by turning the LCD monitor off (p. 12) while shooting.
18
Sample Histograms
Dark Image Balanced Image Bright Image