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3.2 Scanners




by Sunsetstrip See Profile edited by tmpchaos See Profile
last modified: 2002-12-20 22:52:08

Vuescan is a constantly upgraded scanner driver, available for (M) (U) (W), that is very highly customizable.

by tmpchaos See Profile

You typically want a film scanner because you have some old negatives or slides and want to convert them to digital, or because you still shoot film but want to take advantage of the digital darkroom. While only a few years ago you needed a lot of spare cash to get your hands on a film scanner, today you can get great results for well under $1,000, and professional quality for just a little more. But with the wide range of offerings, you need to know what to look for.


There are two main categories you will be looking at: dedicated film scanners and flatbed scanners with film scanning capabilities (the third family, drum scanners, is still out of everybodys budget, except perhaps Bill Gates). Lets take them in turn.

Dedicated Film Scanners

If you are positive that you will never want to scan prints and will only want to deal with negatives and slides, then a dedicated film scanner will offer you better results than a flatbed (although the gap has been narrowing lately). Dedicated film scanners have no glass between the transparency and the sensor (which is normally a CCD, just as in most digital cameras), and the build and focusing ability of the scanner is optimized for film. Both Nikon and Minolta make consumer-level dedicated film scanners in the $400-$500 range.

Flatbed scanners with transparency scanning capability

If you want to have the additional flexibility of being able to scan printed documents, then you may want to look into flatbed scanners. Here again scanners are divided into those with a separate transparency processing unit (TPU) and those with a transparency adapter. The transparency processing unit is actually a second scanning lamp, built into the lid of the scanner, that only comes into play when scanning transparencies. Scanners with a transparency adapter use the same lamp for scanning film and prints. All other things equal, scanners with a separate TPU will yield much better results when scanning film. Canon and Epson reign supreme in the field of flatbed scanners with separate TPUs.

An advantage of flatbed scanners is that, since the scanning area is bigger, they will have medium format film holders, which you will only find in the very high-end dedicated film scanners. Flatbed film holders, however, will many times fail to hold your film perfectly flat, and moir artifacts can appear in the final image as a result. Many people tape the negatives to the scanner glass, or place them between two pieces of glass, to ensure that they are perfectly flat. Since flatbed scanners do not have an autofocusing system like dedicated film scanners, however, you need to experiment to find the optimal arrangement while keeping your film at the scanners optimal focusing distance.

What makes a good scanner?

Optical resolution:

As with megapixels in digital cameras, the optical resolution of a scanner, measured in DPI (dots per inch) is one of the main determinants of how much detail the sensor will be able to capture. But, just as in digital cameras, resolution is not the be-all-end-all. The following important qualifiers are in order:

- Quality of the sensor: Just as in digital cameras, scanner CCDs are subject to noise as the resolution increases and the size stays constant. Make sure you are getting a sensor of the optimal size for your target resolution. A good-quality sensor at 2400 dpi will be able to capture more detail than a bad-quality one at 4800 dpi.

- Input material: Most detail in consumer film will be captured by a 3200 dpi scan. Increase the resolution and youll just be scanning the grain in the film. Unless you have professional-grade film, there is no point in scanning at higher resolutions.

- Target output: think of what kind of output you want from your scanner. A 2400 dpi scan from a 35 mm negative is 4200x3000 pixels (or 12.8 megapixels in digital-camera-speak), for a whopping 36 MB of uncompressed information. At 4800 dpi, that becomes a 8400x6000 pixel image (50.4 megapixels), and a ridiculous 144.2 MB of uncompressed information. Do you need images that big? A good 2400 dpi scan will print fantastically at 20x30.

Scratch and Dust Removal:

Negative film, if not preserved in archival quality holders and in a fairly aseptic environment, is going to collect dust, some of which will stay on the film strip even after careful brushing, and will be very susceptible to scratching. While you may not see these small defects in a 4x6 print, they are going to scream in your face in a monster-sized scan. Most scanning software packages, as well as Photoshop, have dust and scratch removal features, but they are either very time-intensive or will degrade the quality of your picture beyond recognition, while failing to catch all of the defects. Fortunately, a much more efficient hardware-based alternative exists.

The concept of hardware-based dust and scratched removal is based on the insight that dust and scratches are physical alterations of the film surface. Scanners with this feature use a separate infrared lamp to scan the film a second time; infrared light does not catch any of the film colours, but is reflected by the dust and scratches. The scanner then subtracts the infrared image from the colour one, and presto. The trademark names for this technology are FARE (Canon) and Digital ICE (Nikon and Epson). Be aware that using either FARE or Digital ICE can multiply scanning time by a factor of 5, or even more, depending on the resolution.

Scanning time:

So you have 3,000 negatives you want to scan. Can you make this a weekend project? Unless your definition of weekend spans a couple of years, not a chance. Scanning, particularly at high resolutions, takes time, and lots of it. Scanning time increases with the size of the input material, the target output resolution, dust and scratch reduction, and is inversely proportional to the price of the scanner. As a reference, scanning a 35 mm negative at 3200 dpi on my Epson Perfection 4870 (current top-of-the-line in Epson flatbeds) takes two and a half minutes. If you add Digital ICE dust and scratch removal, which I find to be almost always essential, that becomes 12 to 15 minutes. Add another five minutes per image for fine tuning the cropping, colour and contrast, and you end up with three, maybe four scans per hour. Your 3,000 negatives will take 1,000 hours of uninterrupted work to complete (and a lot of storage space). If you have that many, you may want to consider a scanning service.

That said, if you are willing to compromise on the fine tuning, there are options to automate the process. Epsons scanning software automatically recognizes and crops negative and slide frames. Nikon has a negative film roll for its mid and high-end dedicated film scanners, which will hold an uncut roll of up to 40 frames and automatically scan them all at the touch of a button. As always, there is compromise between that last 5% of quality and the time that youll need to put into achieving it.

Data Transfer Interface:

You read well: a 2400 dpi scan consists of 36 MB of uncompressed data. To transfer those humongous files, you need a fast transfer interface. Make sure your scanner supports USB 2.0 or FireWire (IEEE 1394); otherwise, youll find yourself waiting forever as a slow USB 1.1 connection adds an extra five minutes of transfer time to every scan.

Can I get this for really cheap?

Quality, scanning time, and price: pick any two. If you want to keep things on a budget and still get high quality pictures, gear up for long waits before your scans are ready. The low-end dedicated film scanners, as well as the high-end flatbeds with separate TPU will give you almost pro quality for under $500, but they are slooooow. If you are in a hurry, youll have to settle for either lower resolutions or a higher price tag. Mid and high end dedicated film scanners are almost twice as fast, and they start at twice the price. The balance is up to you.


All scanners ship with proprietary software that can do a pretty decent job; most of them will also include the Lite versions of professional scanning software, such as SilverFast, to give you a taste of the more powerful features in the pro versions and entice you to upgrade. The pro version may come bundled with a higher-end edition of the scanner: for example, the Epson Perfection 4870 Professional is the same scanner as the Epson Perfection 4870 Photo; the only difference is that the Professional ships with the pro version of several software packages, while the Photo comes with the Lite versions. Finally, you can purchase non-bundled software, with VueScan apparently being the favourite of the masses.

Again, there will be a trade-off between ease of use and fine tuning. Most scanner software will have a one-touch scanning feature, but if you care at all about dynamic range and color balance you will want to steer clear of it. As you move into more elaborate software packages you will find more buttons, dialog boxes and sliders to fiddle with, but it will take more time and practice to master them.

As a rule, if you own and know how to use an advanced image editor such as Phtoshop, PSP, etc, do as little as possible editing on the scanning software itself. The processing functions in dedicated image editors are much more powerful, and will give you more leeway in sprucing up your image.

If you want to scan many images, you will want a software that makes batch processing easy. The Epson software, while not the best at getting colours and dynamic range right, is great for automatically identifying, cropping and scanning many frames at once. VueScan, on the other hand, while very powerful at the individual image level, is a pain in the neck to use in batch mode. Youll have to find out what works for you.

Finally, some software will allow multiple-pass scanning (VueScan does, as does the Nikon software). Multiple-pass scanning scans the same image many times, and then creates a composite image comparing the data it collected in the different passes. This has the effect of dramatically reducing sensor noise, which is random and therefore gets averaged out in the multiple passes. The price: multiply the scanning time by the number of passes.

The bottom line

If you fall in the category of people that built a collection of film photographs before moving to digital and want to move them to a digital support, you should be comfortable with either a high-end flatbed or an entry level dedicated film scanner. As long as the flatbed has a separate TPU, the quality of the output will be almost the same as in an entry-level dedicated film scanner. Epson and Canon high-end offerings are both safe bets.

If you expect from your scans a quality similar to that produced by mid-range dSLR cameras, then youll have to consider the mid and high-end dedicated film scanners, and your budget will have to start at around $1,000. Nikon and Minolta have collected many praises in this field.

Happy scanning!

by Mauricio9 See Profile edited by DavisPhotog See Profile
last modified: 2004-07-18 23:20:26