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Fine Print Imaging – Drum Scans – Negative Film Scanning – Slide Scans
Drum scanning
A drum scanner is made up of a rapidly spinning cylinder to which an image, most commonly a transparency or negative, is taped. A full spectrum light is beamed through the image on the drum and is read by a photo-multiplier tube (PMT), which is a vacuum tube that encloses a phosphor sensor. In the PMT the phosphor screen is scanned and cleared thousands of times every second as each pixel is read off the image.
Most consumer flatbed scanners use charge-coupled device (CCD) technology. This technology is mechanically simpler and easier to mass-produce, which is why CCD scanners are much cheaper than drum scanners. The sensing component in a flatbed scanner is a chip with an array of several thousand CCDs arranged in a line.
According to an article by Jim Rich, www.digitaloutput.net, “The heart of the PMT verses CCD debate is based on how shadow details are captured by scanners. Drum scanners using PMTs are known to have better shadow details due to less electronic noise. This enables the scanner’s sensors to distinguish more clearly between density areas in originals. The result is more shadow details and less grain. Some CCD-based scanners struggle with detecting shadow details. The resulting scan can lack shadow details and become grainy.
So what’s that mean to you? The bottom line is that the flatbed scanner you buy at Best Buy or one of the other Big Box stores will not produce files with the same clarity, sharpness, separation of tonal detail and dynamic range as you will get from a drum scanner. At Fine Print Imaging, we have used ICG drum scanners since 1999. The closest competitor to the ICG scanner is the Tango.
It should be noted that not all flatbed scanners are created equal, and there are some very high-end flatbed scanners capable of producing excellent results. But these are not the $249 scanners that also serve as a fax machine. High-end flatbeds will cost upwards of $50,000.00, about the same price as new drum scanners.
What are flatbeds good for? Scanning small 2-D art and photographs (some can scan 35mm slides as well) for web use and small printing purposes, such as note cards and postcards. If you shoot 35mm film and want to make sure you are getting every detail in your slide, or if you shoot medium or large format film, drum scans are the way to go.
