Buying Guide: Document scanners
Do you yearn for a paperless office, dream of being able to search your paper files as easily as your digital files, or simply want to reduce paper clutter? In all these cases, your goal is to turn all those piles of paper on your desk, and the contents of your bulging filing cabinets, into PDF documents that look exactly like the originals—and have searchable, selectable text. The best tool for this job is a document scanner.
When you need a document scanner
As the name suggests, document scanners are optimized for large volumes of documents—primarily letter- and legal-sized pages consisting mainly of text. If you’re looking at reams of business or academic papers, or personal documents such as receipts, bills, medical records, and tax forms, a document scanner is just the thing. (For more on converting to a paperless office, see “How to make your office paperless” or my ebook Take Control of Your Paperless Office.) On the other hand, with a few notable exceptions, document scanners are not what you want if you mainly need to scan photographs, slides, books, magazines, or anything thicker than card stock.
Most modern document scanners have a compact, upright design reminiscent of fax machines—you load pages to be scanned into an automatic document feeder (ADF) at the top, and they come out in a horizontal tray in the front. The scanners invariably include software that can perform OCR (optical character recognition), and are generally speedy enough to churn through dozens of sheets per minute. Operation is simple; after an initial setup procedure, you typically load your document(s), press a button, and watch it go. The pages zip through the scanner, and a few minutes later, searchable PDFs appear on your Mac.
The vast majority of document scanners offer 600 dpi optical resolution. That may not sound very high, as flatbed scanners intended for scanning photos and artwork more typically have resolutions of 4800 dpi or even higher. But when you’re scanning primarily text-heavy business documents, 300 dpi is adequate for highly accurate OCR, and higher resolutions massively increase file size while providing no practical benefit.
Features to look for
When shopping for a desktop document scanner, concentrate on the following core features:
Mac compatibility At the risk of stating the obvious, Mac users want a scanner that includes Mac software. Many document scanners come with software that supports both Mac OS X and Windows, but some scanner manufacturers offer only a subset of their models in Mac-compatible versions.
Scanning speed A document scanner’s speed is measured in either pages per minute (ppm) or images per minute (ipm), where a sheet of paper counts as a “page,” and one side of a page counts as an “image.” Speed may vary according to the resolution you choose, the size of the paper, and whether you scan in color, black-and-white, or grayscale, But most manufacturers use similar assumptions in their specifications (for example, “40 ipm/20 ppm for letter size at 200 dpi”), so you can make meaningful comparisons.
Single-pass duplex scanning A duplex scanner is one that can scan both sides of a page without requiring you to turn the paper over yourself and feed it through a second time. (Those that can scan only one side at a time are called simplex scanners.) This time-saving feature appears on virtually all desktop document scanners.
Most models can scan both sides of a page at the same time, in a single pass. Some duplex scanners with a flatbed design, however, require two passes for a duplex scan—they pull the paper through all the way for the first pass, and then pull it back through along a different path to scan the other side. This two-pass process significantly increases scanning time. The manufacturer’s marketing materials may not spell out which sort of duplex scanning is used, but if the specified ipm speed is exactly twice the ppm speed, you’ve got yourself a single-pass duplex scanner.
Duty cycle The duty cycle is the manufacturer’s rating for how many pages per day a scanner can process comfortably without overheating or wearing out prematurely. For home and small-office use, even a modest duty cycle of 500 pages per day should be more than adequate, but if you plan to keep your scanner quite busy, look for one with a duty cycle greater than the number of pages you expect to scan on a typical day.
Ultrasonic double feed detection An increasing number of scanners can alert you if they detect two or more pages being fed through at once. That’s helpful, although better still would be double feed prevention!
Bundled software Every document scanner includes some software from the manufacturer that enables the scanner to talk to your Mac and lets you configure things like where scanned documents are stored, and in which format. The better ones can automatically figure out whether scanned documents are single- or double-sided, correct skewed images, and perform other helpful processing. OCR software (often provided by customized versions of third-party applications such as ABBYY FineReader or Readiris) is also de rigueur.
But beyond that, some scanners include software with a greater range of features, such as image editing or document management. And a few offer software that can automatically process business cards or receipts, pulling out specific bits of data from the scanned images and storing them in appropriate database fields.
Price and extras Document scanners targeted at consumers and SOHO customers tend to have retail prices below $500; significant discounts are often available. If you need to process larger volumes of paper or share a scanner with others in your office, look for a “workgroup,” “departmental,” or “production” scanner. These can range in price from $500 to well over $10,000 (with quite a few in the $1000-to-$1500 neighborhood), depending on features and speed. Among the extras you can find in these higher-end scanners are larger ADF capacities, vastly higher speeds, duty cycles in the tens of thousands of pages per day, Ethernet connections, and built-in Web servers for remote management.
Trade-offs and special cases
Although a standard desktop document scanner is ideal for many people, your specific needs may induce you to look for something a bit different. You should be aware of some special scanner varieties, and what their limitations are.
Portable and convertible models Most scanners that bill themselves as “portable” or “mobile” lack an automatic document feeder (ADF), which disqualifies them as document scanners under the usual definition. However, portable scanners with ADFs do exist, and some desktop scanners have a detachable ADF so that you can have a full-featured document scanner on your desk, and a less-featured (but much more compact) scanner to travel with.
Portable scanners may run on USB bus power, but sometimes require two separate USB cables. And portable scanners are nearly always slower than their desktop counterparts. On the other hand, some manufacturers offer portable scanners with built-in memory or support for memory cards, so you can scan without having a computer with you. Finally, a few ultra-portable, wand- or pen-shaped models exist too; they lack any feeder at all, and you simply swipe them over the page (or portion thereof) you want to capture.
Flatbed design A few document scanners are designed as a flatbed scanner with an ADF on the top. This design makes it possible to scan items that a standard document scanner would choke on. But don’t assume any flatbed scanner with an ADF is, ipso facto, a document scanner.
Check for other features such as speed and bundled OCR software. Be aware that many flatbed scanners with ADFs support only simplex (single-sided) scanning, and of those that support duplex scanning, some require two passes per page, which slows them down.
Multifunction printers A multifunction printer (MFP) is a device that combines several functions—typically a printer, scanner, copier, and fax machine. These are tempting because they save space, but most MFPs make poor document scanners because except in a few rare cases they lack duplex scanning, at least of the single-pass variety; they also tend to be slower than stand-alone scanners.
Senior contributor Joe Kissell is the senior editor of TidBits and the author of the ebook Take Control of Your Paperless Office.