Measurements: What About the Trays?
Some manufacturers' measurements include the input and output trays for
their scanners, but many don't. In the real world, that extra few inches for a
tray can make the difference between a scanner fitting or not fitting where you
as a spec can mean either a duplexing scanner that scans
both sides of the page at once or a duplexing ADF (automatic document feeder)
that scans one side, turns the page over and scans the other side. The more
meaningful specs to look for are pages per minute (ppm) and images per minute
(ipm). For duplexing scanners, the ipm is double the ppm.
Pages Per Minute: At What Settings?
The ppm ratings for document scanners can vary greatly depending on the
resolution and color mode settings (black and white, grayscale, or color).
Scanner manufacturers are usually good about stating the settings, but
different manufacturers base their ratings on different settings.
When Pages Per Minute Doesn't Matter
Most document scanners come close to their rated speed when scanning to
image files. But some slow down a lot more than others if they're also
recognizing text and saving the scan as, say, a searchable PDF file. If
recognizing text is part of what you need from a scan, the faster scanner will
sometimes be the one with the slower rating.
Legal Size Paper
Being able to scan legal size paper doesn't
necessarily mean a scanner has a legal size flatbed. With most scanners that
have an ADF, you can scan legal size paper even if the flatbed is letter size.
(Having an ADF doesn't necessarily mean the scanner can scan legal size