Canon POWERSHOT SX100IS User Manual page 72

Commonly Used Shooting Functions
I 71
_ Configuring the Postcard Mode []
See Functions Available in Each Shooting Mode (p. 222).
You can shoot images with the optimal settings for postcards by
composing them inside the print area (width-to-height ratio of
approximately 3:2) shown in the LCD monitor.
The digital zoom or the digital tele-conver[er cannot be used in
this mode.
[_] For printing instructions, refer to the Direct Print User Guide.