Plustek Mobile Office S420 portable document scanner

The Mobile Office S420 is a sheet-fed scanner for documents and business cards, able to scan a single sheet at a time.

It comes in two parts: the main one, the scanner itself, is small at around 29cm (a touch under a foot) wide. It's roughly the same size as the Fujitsu Scansnap S1100 and like that model it's portable.

The scanner connects to the computer using the supplied mini-USB cable, and draws power either through the supplied mains adapter or, if you're on the move, you can connect the second supplied USB cable which attaches to the scanner's power port and provides power only.

A black plastic dock is also provided for the device – the scanner clips into this and connects to it using a pair of cables attached to the dock.

This appears to be a ‘feeder', which allows the user to line up several sheets for automated scanning, but in fact it doesn't do that. Instead it has two functions: it has a plastic ‘stop' that ensures sheets are straight for scanning, and it has two USB ports, allowing the single scanner to be shared between two PCs.

Unfortunately the dock is cumbersome and the scanner doesn't clip in neatly, requiring adjustment each time. It would have been better had the scanner automatically connected when clipped in, without the need for cables, and it would have been more useful if it automatically fed documents into the scanner. It closes up neatly, but only when the scanner isn't connected.

The supplied software was wide-ranging: it covers scanning of documents, optical character recognition (OCR) and archiving business cards. We found the latter particularly handy, but it wasn't as polished as the program that came with the Fujitsu scanner, and it's not much use for home users.

Quality overall was fair. We wouldn't use the S420 for photo scanning (and nor is it designed for that) but documents came out fine. The OCR worked well too. It was quick, taking a few seconds for an A4 page at the normal resolution and 30 seconds at the higher one.

But the main scanning software proved quite flaky: it locked up several times, and also threw out the least helpful error message we've ever seen, which just read ‘Generic error'.

When the S420 worked, it worked well, but overall we prefer the more polished experience of the Fujitsu Scansnap S1100.