Fujitsu ScanSnap S1500M Operator's Manual page 417

2.
In the [File format] pop-up menu in the [File option] tab, select [PDF
(*.pdf)].
It is recommended that you select [Better] or [Best] for [Image quality] in the [Scanning] tab
of the ScanSnap setup window.
Using the ScanSnap in Various Ways (for Mac OS Users)
417