Monday, 17 October 2011

Four Types of Scanners


Four Types of Scanners

There are four basic types of scanners or scanning systems to consider for high-quality printing purposes: drum, film, flatbed, and specialty.
Drum Scanners
It used to be that using a drum scanner was the only way to have a high-resolution scan made, and many photographers-artists still purchase drum scans from scanning-service providers. Using photomultiplier tubes (PMTs) instead of CCD chips, old-style drum scanners are big, finicky machines that can take up half a room, although newer, desktop models are now available. The artwork-typically a transparency or a small print-must be flexible, and it is wrapped around a clear cylinder or drum that spins while a focused light source on a track shines through or on it and onto the image sensors. Drum scanners can produce wonderfully large, high-quality images with great dynamic range and resolutions that can approach 12000 dpi. These outsourced scans aren't cheap though figure paying $50-$100+ per drum scan depending on the file size.
Film Scanners
These specialized desktop scanners have become very popular with photographers who want to do their own scanning of negatives or transparencies. Film scanners have taken over the position of drum scanners for many wanting high-quality scans. Instead of the light moving past the original on a spinning drum, here the film moves ever-so-slightly past the light source, which with many brands is a cold-cathode, mercury fluorescent lamp, or, in other cases, an array of LEDs. Depending on the price, film scanners can handle 35mm up to 4 × 5-inch sizes. Because film has to be enlarged more than prints, and also because film has a wider density range and more contrast, most film scanners have correspondingly higher optical resolutions.
A maximum resolution of 4000 dpi is standard for many desktop film scanners with others going even higher. A different type of film scanner is made by Denmark's Imacon, and their Flextight models have a unique way to handle the artwork (several models also scan reflective prints). The film is bent in a drum-like shape except there is no drum! There's only air between the sensor and the film, which is held in place by its edges. They call it a "virtual drum," and there's no need for the mounting liquids, gels, or tape that drum scanners require. The resolution is high (up to 8000 dpi, non-interpolated) and with a price tag to match. Other desktop film-scanner makers include: Nikon, Canon, Microtek, and Polaroid.
Flat bed
 Scanners
Like photocopiers, flatbed scanners are basically boxes with a flat glass plate that you put the artwork on. This can be photo or artwork prints, books, even 3D found objects like seashells. A moving CCD array travels the length of the bed scanning as it goes. Earlier flatbeds could only scan reflective art, but the newer generation can now do a decent job with transparencies and film negatives as well; these are sometimes called "dual-media" scanners. These either use an adapter or special lid construction that allows light to shine from above onto the CCD sensors, or they have special drawers with film holders built into the base of the scanner.
Speciality
 Scanners

There are other scanning systems-including such names as BetterLight, Jumboscan, and Cruse that don't fit neatly into the categories above. These are very high-end reproduction scanners used primarily by museums, universities, and research institutions. The Jumboscan by Lumiere Technology in Paris uses a unique up-to-360-Megapixel 12000 × 30000 pixel RGB or "6 band/13 band multispectral" camera with the largest CCD sensor array in the world: 78 × 195mm in size. The camera and JumboLux elliptical light projectors that sweep across the subject in synchronization with the CCD array can be aimed to scan objects on walls, floors, easels, and copytables.
Vince Martin is the writer for We Print Discs and American Recordable Media - The companies that specialize on affordable digital DVD duplication, CD printing services durable cd/dvd duplicator and other types of media products.


No comments:

Post a Comment