Meaningful Measures

By M. David Stone  |  Posted 2008-02-08 Print this article Print


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 want it.

Duplex Scanning

"Duplexes" 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 paper, however.)


M. David Stone is an award-winning freelance writer and computer industry consultant with special areas of expertise in imaging technologies (including printers, monitors, large-screen displays, projectors, scanners, and digital cameras), storage (both magnetic and optical), and word processing. His 25 years of experience in writing about science and technology includes a nearly 20-year concentration on PC hardware and software. He also has a proven track record of making technical issues easy for non-technical readers to understand, while holding the interest of more knowledgeable readers. Writing credits include eight computer-related books, major contributions to four others, and more than 2,000 articles in national and worldwide computer and general interest publications. His two most recent books are The Underground Guide to Color Printers (Addison-Wesley, 1996) and Troubleshooting Your PC, (Microsoft Press, 2000, with co-author Alfred Poor).

Much of David's current writing is for PC Magazine, where he has been a frequent contributor since 1983 and a contributing editor since 1987. His work includes feature articles, special projects, reviews, and both hardware and software solutions for PC Magazine's Solutions columns. He also contributes to other magazines, including Wired. As Computers Editor at Science Digest from 1984 until the magazine stopped publication, he wrote both a monthly column and additional articles. His newspaper column on computers appeared in the Newark Star Ledger from 1995 through 1997.

Non-computer-related work includes the Project Data Book for NASA's Upper Atmosphere Research Satellite (written for GE's Astro-Space Division), and magazine articles and AV productions on subjects ranging from cosmology to ape language experiments. David also develops and writes testing scripts for leading computer magazines, including PC Magazine's PC Labs. His scripts have covered a wide range of subjects, including computers, scanners, printers, modems, word processors, fax modems, and communications software. He lives just outside of New York City, and considers himself a New Yorker at heart.


Submit a Comment

Loading Comments...
Manage your Newsletters: Login   Register My Newsletters

Rocket Fuel