Техническая Спецификация для Canon DR-F120 9017B003

Configure scanning conditions as follows when scanning documents 
in Long Document mode.

 CaptureOnTouch

Set [Page Size] to [Match original size] under [Scanner setting]. 
-> "Select document settings" on p.40

 Scanner driver

Set [Page Size] to [Match original size] in the [Basic] tab. -> 
"Setting Basic Scanning Conditions" on p.50