While portable scanners certainly offer an impressive degree of convenience, they can be problematic when it comes to processing larger jobs, along with issues keeping pages aligned to achieve professional looking results.
Plustek looks to provide the benefits of a more dedicated device along with the convenience of a portable with the S420, an innovatively designed “hybrid” that offers 600dpi maximum optical resolution and an alleged 12ppm scan speed.
The S420 actually comes in two parts. The core of the device is a slimline portable scanner finished in black and silver with two shortcut buttons, a power and data connection. This can be used as a standalone device in its own right, and is certainly slim enough to carry around in a briefcase while out and about.
In addition to this more traditionally designed unit is what appears to be an automatic document feeder (ADF) stand, which unfolds into a paper tray with its own power and data connections. The scanner unit can then be slotted into the stand to utilise the tray and help both speed up jobs and keep things tidy. Additionally the stand incorporates two data connections so that it can be connected to two computers simultaneously, with buttons at the front manually switching between the first and second PC.
It’s a nice idea, but we were disappointed to note that the scanner doesn’t fit particularly firmly into the stand, and is simply pushed in with no clipping mechanism to hold it firmly in place. This didn’t turn out to affect operation too badly, provided the scanner is pushed in as firmly as possible, but it can pop out of its housing a bit too easily and we have to put this down to a flaw in the design. Additionally, the scanner actually slots into the tray upside down, which did seem a bit strange although obviously won’t impact on general use.
After installing the supplied software and running a short calibration routine we tried out the S420 both with and without the stand, with mixed results.
The first thing we noticed is that the stand doesn’t actually behave as an automatic document feeder. Since there is no provision to retrieve one page at a time, attempting to process a batch simply results in the pages getting stuck. This leaves us to conclude that its main purpose is simply to keep pages properly aligned and offer provision for quick switching between two PCs, which doesn’t seem enough of a benefit considering the inevitable increase in cost price.
Quality is fairly good, though it’s important to remember that this is effectively being judged as a portable bar scanner, so is not really suitable for reproducing documents to a high professional standard. We noticed some inconsistencies in text weight and clarity along with artefacts that didn’t appear to be on the original source document, and though this does improve at higher dpi settings, it means that the S420 is clearly aiming for speed and convenience rather than pure quality.
One benefit is the fact that the scanner can handle paper up to 1.2mm thick, which means high-quality glossy photo prints and business cards can run through with ease. In this instance we judged colours to be pretty accurate, though again subtle details and sharpness are lost to an extent, along with undesirable colour gradations on the resultant images.
The S420 is fast, though: scans at the default 200dpi resolution take just 5 seconds per page, so exactly the 12 pages per minute quoted. At the maximum 600dpi this jumps to 30 seconds per page, and there’s an overhead of an additional 50 seconds when documents are converted to PDF.
Supplied in the package are a range of software utilities to help manage scanned documents, correct images and configure the default parameters for the scan shortcut buttons on the device. The applications supplied do feel rather dated now, though just about every box has been ticked in terms of at least providing the facility to manage documents right from the start.