What is the maximum width of document that you need to scan?
A scanner's format size (image width) is usually the major factor affecting its price.
Go for the size that fits.
After size, image sensor type, colour scanning, optical resolution and speed are
the next major influences on a large format scanner's performance.
CCD scanners usually cost more than CIS based wide format scanners. This is because
they will scan and copy monochrome and / or colour photographs more accurately (more
shades and better colour fidelity). If your documents are mainly blueprints, maps,
CAD or other technical drawings, then a CIS large format scanner will provide sharp,
well defined line details and capture all the colours in the document very well.
However, if you need to scan mounted documents or heavyweight folded originals, a
CCD based large format scanner will produce better results. CCD scanners typically
have better illumination and greater depth of focus that is required when scanning
mounted or badly creased documents.
For years, 400 dpi was accepted as the benchmark optical resolution for a high quality
wide format scanner. Most applications, whether archiving or copying, use images
of between 200 dpi to 400 dpi so any scanner with an optical resolution of 400 dpi
or higher will provide good results. Higher optical resolutions can be very useful
if the document has very fine, closely spaced lines (such as contours on maps), but
stored image file sizes rise very rapidly as dpi increases, as do scan times. Optical
resolution is the true measure of how well a scanner can 'see' fine image details
and lines in a document.
Choice of scan speed is directly related to how many documents you need to scan,
in what period of time and at what resolution. Scanning speeds can be much slower
for 24 bit colour scanning than simple B&W scanning.
For typical technical drawings and maps, we recommend the Contex IQ Quattro series
range of scanners. These CIS based devices will scan up to a maximum size of A0
document at a maximum speed of 14 inch/sec in b&w and 24-bit colour (200dpi).
The CCD based HD Ultra range can handle both technical drawings / maps AND also photos
and poster artwork. Choose between 36”, 42” and 54” widths depending on your requirements.
B&W / greyscale documents can be scanned at a maximum speed of 12 inch/sec b&w and
8 inch/sec 24-bit colour (200dpi).
Alternatives that might be relevant include:
The highly portable Contex SD3600 series scanners that will scan documents up to
36” wide at a maximum resolution of 1200dpi. At 21kg in weight it is (almost) light
enough to be moved between sites at will.
Large format flatbed scanners which are capable of capturing documents that are unsuitable
for sheet fed scanners such as fabrics, fine art, fragile originals, books, bound
documents and materials thicker than 20 mm. Products worthy of consideration include
the Contex HD iFlex and Kurabo range of scanners.