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Tuesday, June 19, 2007

Large-Format Scanning

Discover the alternatives for producing your own scans in-house



Achieving corner-to-corner sharpness is important when scanning your images, and the Flextight system ensures this by providing adjustable focal lengths inside the housing, hence the height of the unit, in addition to utilizing a unique magnetic film holder. Achieved automatically based on the film format being scanned, the optics perform as a long focal length, resulting in less distortion, especially toward the edges of the frame.

While CCDs can be prone to signal noise, particularly when scanning dense transparencies, the Flextight scanners reduce noise by housing the power source outside of the scanner housing and by using a cold cathode tube, which produces minimal infrared waves and, thus, heat. This is particularly important when scanning low-key images where noise can become quickly evident in areas of shadow.

Many photographers often see this system as an excellent compromise between a flatbed and a drum scanner.

Flatbed Scanners

A high-end flatbed scanner also can produce quality digital files that suit many professional needs. For the most discerning eyes and maximum flexibility down the road, consider investing in higher-end units, which range in price from $2,000 up to $8,000.

Flatbed scanners, such as those manufactured under the names of Aztek, Cezanne, Creo, Epson and Heidelberg, all follow a similar design. The digital file is produced by placing the film between a glass plate and a light-emitting adapter. The light passes through the film, onto the CCD and then is converted by an analog-to-digital converter into a digital file. With such scanners, it's extremely important to keep the glass clean to minimize the appearance of dust and dirt in the scan. Many flatbed scanners include software that automatically detects and removes dust and scratches.

Some high-end scanners share the same resolution as drum scanners, but it doesn't automatically equate to similar quality. This is because CCDs can produce greater signal noise, which is particularly evident in the shadow areas. Although some scanner manufacturers advertise a dynamic range higher than the theoretical maximum of 4.0, they may achieve their figures by increasing or amplifying the gain, which results in greater noise.

For many, the image quality and enlargement sizes that these scanners deliver may satisfy both a studio's quality demands and budget. With a well-exposed piece of film with moderate magnification, it can be difficult to tell the difference between a scan produced by a high-end flatbed scanner and a drum scanner.

Drum Scanners

Providing resolutions as high as 11,000 dpi and more, drum scanners produce digital files that can lead to exceptional enlargements of more than 800%, in addition to offering a wide dynamic range with minimal noise. Achieving this high image quality requires a precise and consistent workflow.

Unlike other scanners, a drum scanner involves the wet mounting of film to the translucent drum. Using special oil that bears the same refractive index as film, the film is taped to the drum, which then rotates at high speeds. A laser hits that film and the concentrated light is picked up by the PMT. It's the PMT's incredible sensitivity to light that provides the superior image quality.

Prices range from $5,000 to as high as $45,000 and more. While the higher price point reflects an increase in image quality, it doesn't reflect the time involved in learning to make the best use of these units. Considering the expertise required to get the most from a drum scanner, you're probably better served by going to a lab with a reputation for excellent scans, rather than spending the money on a unit for your studio. By doing so, you'll be leaving drum scans in the hands of a qualified technician and you'll get the best results.

Resources

Aztek (800) GRAPH-55 www.aztek.com
Creo (800) 929-9209 www.creo.com
Epson (800) GO-EPSON www.epson.com
Hasselblad/Imacon (Flextight) (973) 227-7320 www.hasselbladusa.com
Heidelberg (888) 472-9655 www.us.heidelberg.com
Hewlett-Packard (800) 752-0900 www.hp.com
Screen USA (Cezanne) (847) 870-740 www.screenusa.com

 

 



 

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