Canon MB5100 Series Online Manual page 276

Tap B to display the screen for selecting the number of copies.
Tap a number to specify the number of copies, and then tap OK.
Tap C to display the preview screen.
As you view the preview at left, drag the slider (E) up or down to reduce or enlarge the image.
You can also tap or (D) to reduce or enlarge images. Keep touching or to adjust
magnification continuously.
After you have the desired magnification, tap OK.
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