Buying Guide: Document scanners
20.05.12
.) 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.
Source: ARNnet