Canon ZOOM 8-3 - Manual (Page 17)

3. Then, look through the viewfinder. You will see a vertical
indicator and an index mark above fine viewing frame.
The needle runs across horizontally to the right and left
as you rotate the aperture scale ring. Correct exposure
can be obtained automatically by rotating and adjusting
the aperture scale ring until the needle seen in the view­
finder aligns with the index mark. (The needle represents
the pre-set film and filming speeds.)
It is important to match them exactly when shooting in
color; however, when using black-and-white film, less
accurate exposure may be allowed. In this case, the
adequate exposure is obtained unless the needle swings
out of the deeper part of the window in which the ne­
edle runs
The diaphragm is opened one stop larger than the
adequate value when the needle is swung to the left and
or>e stop smaller when it remains on the right side.
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