IntroductionTo make high-quality scans from 35mm film, you need a dedicated film scanner. But while flatbed-scanner prices have been in freefall for several years, film-scanner prices have remained in the realm of professionals and very dedicated amateurs - until now. Judging by the four slide scanners we looked at in this review, film scanners are finally coming within the reach of Mac users who don't want to spend a bundle. We looked at SmartDisk's £189 SmartScan 2700 and £349 SmartScan 3600, and Minolta's £299 Dimage Scan Dual III and £549 Dimage Scan Elite II. The SmartDisk scanners are 35mm only, while the Minolta scanners offer an optional adaptor for scanning APS (Advanced Photo System) film format, and all four have OS X-compatible drivers. While we found some flaws and limitations, we were pleasantly surprised by just how well these scanners performed. The SmartScan 2700 is a bare-bones, but capable scanner. The SmartScan 3600 offers automatic batch scanning of film strips containing as many as six frames, and it has more sophisticated editing features than its less expensive sibling. The two Minolta scanners are almost identical; they differ in that the more expensive Dimage Scan Elite II includes Applied Science Fiction's Digital ICE surface-defect removal and Digital GEM grain-reduction technologies. Pixels and detail
It's tempting to equate a scanner's resolution - the number of pixels per inch (ppi) it captures - with its ability to capture detail from film. The SmartScan 2700 has the lowest resolution of the four, with a maximum optical resolution of 2,700ppi, followed closely by both Minolta scanners, with 2,820ppi. The SmartScan 3600 captures 3,600ppi, so you might expect that it would produce the most detail. But we found that the SmartScan 3600 didn't extract any more usable detail than the other scanners; it just made a bigger file. The optics in the SmartScan 3600 aren't particularly sharp, negating any advantage that the higher resolution might confer. And its manual-focus option proved useless because the only feedback that was offered when we adjusted the focus was a postage-stamp-size preview of the whole image. The SmartScan 2700, on the other hand, produced extremely sharp scans, comparable to those from the three other scanners. Resampling the images to the same pixel count in Adobe Photoshop produced results that were nearly identical, in terms of sharpness, from all four scanners In terms of resolution, none of these scanners can compete with the more expensive, 4,000ppi Nikon SuperCoolScan 4000 (£1,299) or the much more expensive, 8,000ppi Imacon Flextight 848 (£10,995) - and nor would we expect them to. We won't enter the debate about how much information a piece of 35mm film can carry, but 35mm cameras in the hands of amateur photographers using consumer-grade lenses produce film that contains a great deal less information than 35mm cameras in the hands of a professional using a professional-grade lens. These scanners can produce good 8-x-10-inch prints from the majority of consumer images. If you're scanning high-speed (400 ISO or faster) film shot with a point-and-shoot camera, these scanners will very likely deliver everything that's on the film. Speed and connectivity
The SmartScan 3600 supports FireWire and USB; the SmartScan 2700 supports only USB. The Minolta scanners use USB 2.0, which is backwards-compatible with the Mac's USB 1.0 implementation. We expected the SmartScan 3600 to be the fastest due to its FireWire capability, but in practice it didn't. The Minolta scanners did, however, produce a much faster pre-scan than the SmartDisk ones, at around six seconds, compared with 20 seconds for the SmartScan 3600, and approximately 30 seconds for the SmartScan 2700. Film handling
The SmartScan 2700 scans one frame at a time, either from mounted slides or from strip film. In either case, you must load the film manually into the scanning window. The SmartScan 3600 can scan either a single mounted slide or a filmstrip that contains three to six frames. Mounted slides feed into a slot on the front of the scanner, while the filmstrips feed, without a holder, into a slot on the side. Software controls let you advance the film one frame at a time, or you can set the scanner to scan the entire strip as a batch. The Minolta scanners use holders that can handle four mounted slides or a six-frame strip of uncut film. You can configure the software to scan all the images as a batch and use the same settings, either auto or manual, for each image. Dynamic range/shadow detail
One of the more confusing aspects of scanner specifications is dynamic range - the range of tones from black to white that a scanner can record. Measured on the logarithmic Optical Density (OD) scale, dynamic range is limited by the analogue sensitivity of the sensor. The whitest recordable white is determined by the point at which the sensor becomes saturated, creating a condition called blooming, where current spills over into the adjacent sensors, creating a white blob. This is often a problem with digital cameras, but blooming rarely occurs with scanners. For scanners, the limitation is the darkest recordable black, determined by the point at which the noise in the system overwhelms the weak signal produced by low levels of light. But just when the signal can be considered ‘overwhelmed' is a subjective decision, so while dynamic range specifications are somewhat useful in comparing two scanners from the same vendor, they're almost useless in any other type of comparison. SmartDisk claims that the SmartScan 3600 has a dynamic range of 3.6D, but at the time of this writing, no spec was available for the SmartScan 2700. Minolta claims that both of its scanners have a "computed" dynamic range of 4.8 - standard test targets don't even begin to approach such high densities. The only reliable way we know of to compare scanners' dynamic range is to scan the same high-contrast slide on each one and compare the results. The two Minolta scanners performed almost identically, seeing much further into the shadows, with much less noise, than the SmartDisk scanners. The SmartScan 2700 actually seemed to have slightly less shadow noise than its higher-resolution sibling. Bit depth
A scanner's bit depth determines the number of discrete shades into which its dynamic range is divided. The SmartDisk scanners use 12 bits per channel, while the Minolta scanners use 16. A wide dynamic range needs more bits to produce smooth gradations than a narrow one, but the real benefit of many bits is editing headroom. If you don't use those extra bits, by either making your edits in the scanner software or bringing high-bit scans into an editing application that can handle them, they're wasted data. If you plan to scan into Photoshop, you should scan a high-bit file. But the SmartScan 3600 driver has a bug that prevents it from scanning high-bit files at its maximum resolution - it scanned high-bit files at resolutions as high as 3,000ppi, but when we tried to scan high-bit images at a higher resolution, we got the dreaded spinning beach ball. After leaving it overnight, we had to force-quit Photoshop. If you use Adobe Photoshop Elements, you can scan only to an 8-bits-per-channel file because Elements doesn't support high-bit images. To get the benefit of the extra bits, you need to use the controls in the scanner's software to optimize your images. Editing controls
All four scanners let you scan through either a stand-alone utility or a Photoshop-compatible plug-in. (The Minolta scanners include Adobe Photoshop Elements 1.0, which isn't OS X native, so we did our testing using the plug-ins and Photoshop 7.0.1.SmartDisk includes OS X-native Photoshop Elements 2.0). The biggest limitation of these scanners' drivers is that they force you to make your edits based on a fairly small pre-scan. The SmartScan 2700 has the most-limited software, with a preview close to actual size, and no readout of RGB values. The SmartScan 3600 offers RGB readouts and a zoomable preview window, but it simply magnifies the pixels in the pre-scan, so you see a large, blocky image instead of a small, smooth one. The Minolta scanners' software previews have a somewhat higher pixel count, but they're still too small to allow you to set black and white points precisely. All four scanning plug-ins include curve- and histogram-based editing tools, and slider controls for brightness, contrast, and colour balance. They all let you specify a monitor profile for accurate display and an output profile for scanning into the host application, so what you see in the pre-scan matches the final scan in the host application. The Minolta plug-ins also offer selective colour-editing controls. The scanners' automatic exposure and colour balance worked well on positive slides; less so on colour negatives. (We've yet to find a scanner that consistently produces good automatic results on colour negatives.) If colour-negative scanning is important to you, plan to edit each image individually - but you'll have much less work to do with the Minolta scanners than with the SmartDisk models. Defect and gain The Minolta Dimage Scan Elite II includes Applied Science Fiction's Digital ICE and GEM, which involve additional hardware in the scanner as well as special software. They work extraordinarily well. You shouldn't confuse ICE with a pixel-cloning scheme that attempts to repair defects with software only. ICE uses invisible wavelengths to map surface defects such as dust specks and scratches, and lets the scanner see behind defects and repair them automatically. GEM reduces obvious film grain that can interfere with image detail. It's particularly valuable on scans of colour negatives, because during the editing process, the grain on colour negatives becomes much more exaggerated than the grain on slides. However, GEM is also useful on other kinds of originals.