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BUYING GUIDE: Film Scanners
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BUYING GUIDE: Film Scanners

Want to digitize your slides and negatives? Here's what to look for when buying a scanner

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It's easy to convert negatives and color slides and into high resolution digital images. And isn't it about time?


Somewhere in your attic, closet, or in the drawer of an old desk you have a collection of negatives. Even if your first camera was a filmless digital model, odds are you have some negatives or slides somewhere. All families do. They could be precious images of your ancestors, friends, or baby's first step. They should be digital images--and now they can be.

Once scanned, all of those images can easily be printed, shared by e-mail or edited the same way you'd edit any digital image. They can also be stored in a digital vault for safekeeping (see our sidebar on Image File Storage options).

There are several scanner equipment options. All require a computer but none require any special skill to produce outstanding results. Here's a rundown of the things you need to know about digital film scanners.

STYLE

If you are planning to scan a large number of negatives, buy a dedicated film scanner. They deliver the best performance and produce the highest quality images. Some flatbed scanners will also scan negatives and slides, so if you need to make only a few scans and don't mind the lower resolution you may find a flatbed or printer-scanner combination more versatile. Dedicated film scanners do a better job of scanning film than do multifunction machines--resolution is much better on dedicated units; however, all they can do is scan film. Flatbed scanners and scanner-printers can provide many other functions around the home or office.

FILM FORMATS

Most film scanners work with 35mm film. Some can scan APS film with an optional adapter. If you must scan larger film formats, like 2 1/4 (6x6cm) and sizes up to 4x5, make sure the scanner you buy works with those sizes.

OPTICAL INPUT RESOLUTION

When it comes to digital cameras we talk about megapixels. With film scanners we classify them by input resolution and refer the "dpi" (number of dots per inch). The higher the number, the higher the resolution.

But there's a catch: Optical resolution is very different from Interpolated resolution, and confusing the two can adversely effect your buying decision.

Just-scanned slide: Here's what a slide looks like right after it's been scanned, with no manipulation. Note the rounded black borders--that's where the mount starts.
Fixed up: Scanner software may let you crop out borders, adjust color balance, and even remove dust. I adjusted the balance before scanning, but did the rest in Photoshop Elements.
SCAN METHOD AND TYPE

When you look up the purely technical description of the scanner type, what you'll probably find written on a film scanner's spec sheet is something like: "moving-film, fixed-sensor, single-pass scan with 3-line color CCD," or words to that effect. Simply translated, the film is transported over a CCD imaging sensor in a single pass to create the scan. There are other methods but this one is the most common. Light sources vary by brand. Some use cool-burning LEDs, others use fluorescent tubes or other methods.

SPEED

Fast scanners can produce a pre-scan (a low resolution-scan of the image, used for fine-tuning color, contrast, and other settings before the more time-consuming full-resolution scan) in less than 15 seconds, and a full-resolution scan in under a minute. Always check the speed specs. If it's real speed you're after, make sure that the scanner will accept "batches" of slides, either in an extended carrier or in a cartridge-type magazine. Otherwise you will waste a lot of time loading slide carriers.

INTERFACE

Operational speed is only part of the scanning speed equation. Another part is how long it takes to transfer the digital data to a PC for processing. Look for a unit that uses high-speed USB (USB 2.0) or Firewire (IEEE1394, also known as iLink). Anything else is just too slow.

A/D CONVERSION (literally, Analog-to-Digital Conversion) is normally done in either 12-bits or 14-bits per each of the three color channels. A 12-bit A/D converter produces up to 4,096 levels of information (e.g. shades of a color) per channel whereas a 14-bit converter produces up to 16,384. A 16-bit machine punches out 65,536 levels per channel. What to remember? The higher number is better.

DYNAMIC RANGE is a frequently abused specification. If we determine a device's dynamic range by simple calculation, a 12-bit device has a range of 3.6 and a 14-bit device provides a dynamic range of 4.2. Strictly speaking, this is impossible. When determined by actual measurement, pure white is represented as 0.0 (zero) and pure black as 4.0. A measured dynamic range must fall between 0 and 4.0. The purpose of the specification is to indicate the scanner's ability to render shades of grey that begin at pure white (highlights) and extend through pure black (shadow detail). A higher number is better, but take this stat with a moderate grain of salt.

FOCUS METHOD

You want autofocus, of course, but it's nice to have manual focus, too. Film scanners do a good job of focusing slides and negatives, but some film, especially old mounted slides, can be a bit curled. Tweaking the focus puts things back in order.

FIRMWARE/SOFTWARE

Software options sometimes include useful programs like Adobe Photoshop Elements or one of the various DAM (Digital Asset Management) tools that help you keep track of your image library. Firmware, or combined firmware/software options, are actually much more interesting. Many film scanners can eliminate the degrading effect of scratches and dust, restore faded colors, reduce apparent film-grain size and make other corrections because they have powerful built-in firmware (like Digital ICE) that automatically processes the images to produce optimal results.

SYSTEM REQUIREMENTS

Finally, don't forget to check the system requirements, especially if you drive a Mac. If your PC is less than a year old you should have no trouble. In any case, check the specs and make sure that your computer has enough RAM and processing power to handle the film scanner. Also make sure that you have enough storage space to save all of those images you'll be creating. If you come up a bit short, check the sidebar.

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