Review of Linux Compatibility
The Canon CanoScan FS4000US is a scanner for slides, 35-mm film negatives or APS film. The scanner has a resolution of up to 2710 dpi with a color depth of 36 bit.
The FS4000US can be connected via USB and via SCSI. The scanner has the USB ID 04a9:3042
Bus 001 Device 002: ID 04a9:3042 Canon Inc.
and is recognized by SANE
sane-find-scanner: found USB scanner (vendor = 0x04a9, product = 0x3042) at device /dev/usb/scanner0
However, the CanoScan FS4000US is not supported by SANE, independent if USB or SCSI connection is used.