Overview
Running through the specification, we note that this machine has an optical resolution of 3200dpi and 48 bit colour - this combined will translate to an uncompressed file size around 70MB in size, and if scanning in 24 bit (8 bit/channel for a colour scan) a 39MB file size is achieved. So far, so good - these dimensions will produce a 15"x10" print at 300 dpi. Until recently, pro-sumer dedicated film scanners were rated at this resolution, with only the latest machines scanning at 4000 dpi upwards, so one can assume that in the vast majority of cases 3200 dpi should be enough for the enthusiast.

The film adaptor unit (FAU) appears well made, and it is designed to be clipped securely into the lid in only one orientation ensuring that the media is correctly aligned. This results in the software knowing exactly where to scan and crop to very effortlessly display each frame in the scanning software - no dragging crop boxes around. In the preview you will be presented with 2 (slides) or 4 (strip) frames, already cropped and each one can be selected for individual file output.

The speed at which this scanner operates is one of it's strongest marketed features. Document scanning is a breeze, but since we are not concerning ourselves about that here, previewing film scans is slower but quite acceptable. Canon's claim to 2.6 seconds is clearly relating to previewing a document from the platen, whereas a strip of 4 colour negatives preview in approximately 55 seconds. This figure is from the moment the preview button is pressed to the previews appearing complete on the screen, including adjusting the lamp which is necessary each time the lamp has been turned off (user configurable 4, 8 or 12 minutes). Subsequent scan take around 30 seconds, so long as the lamp does not timeout in between, this figure increasing to 40 seconds if the software is configured to calibrate on each scan.

Software
In all, four distinct software tools are supplied with the unit, not including the ever-present Acrobat Reader. During installation from the single CD you may select which of these are installed. One is the character recognition software which we will not discuss here (I have not installed it), another is a small toolbox which controls the very basic functions of the scanner, including configuring what occurs when one of the scanner mounted buttons are pushed. A third is ArcSoft PhotoStudio 5.5, which is an image editing tool I have no experience of. If you do not currently use one of the main players in this field, Photoshop, Elements or PaintShop Pro for example, then this may well be a bonus. The final one, and the one of interest here is ScanGear CS (this seasons suffix of choice) - which is the scanner acquisition software that will be called vie the TWAIN interface whenever you request to scan something.

Fig 1. ScanGear CS control panel in advanced mode

ScanGear CS has a simple mode, which I dispensed with rather rapidly as it does not give an option to scan Black & White negatives - the film I loaded into the scanner upon first using it. Once again taking the stance as a enthusiast, you are unlikely to be settling for the simple mode - and the advanced mode is not exactly daunting. In advanced mode you gain control over a few extra parameters - and the option to scan B&W negatives.

The software provides the user to select whether unsharp masking is used or not. As far as control over sharpening goes, that is it. It is either on or off. When set to apply unsharp masking I have seen little in the way of beneficial sharpening, the images itself seems to gain very little in edge sharpness while the noise is exaggerated by the sharpening. I believe that sharpening images from this scanner is best left to your imaging software. Using the Focalblade plug-in for Photoshop produced sharpening in the right places, whilst managing to avoid the noise.

As promoted in the specification, this scanner includes "QARE Level 2 dust and scratch removal from photographs". The important part of that statement from a film scanners point of view is "photographs" - the option is disabled in all modes except for "Platen" and is not available in any film mode. If you are scanning some prints, then it may do a very good job - but your damaged negatives or slides will need fixing in another application. This may not be such a bad thing, as without an infrared based repairing tool as the higher end scanners feature, it would do little for your cause.

Two other tools are provided for improving defects, Fading Correction and Grain Correction. These each have four intensity settings, including "none" - which is the setting you should leave them on if you plan any touching up in imaging software after the scan. Fading correction makes a solid attempt at restoring colours from faded media by exaggerating the film terms conversion and bumping colour adjustment. You can do a better job in Photoshop, but of course it is more time consuming. The same can be said about grain correction, only to a stronger degree. The ScanGear software does smooth out grain, but it is not close to plug-ins available for imaging software - which are almost as simple to use.

By default, the option to output 48 bit files is disabled - to enable it you need to enter the Preferences dialogue. There are various other settings in here, including allowing the user to set the lamp timeout period and customise the colour management settings. I will discuss colour management in a little more detail further on.

The "Color" tab contains a number of useful manual tools for making tonal and colour adjustments. These consist of a basic brightness/contrast slider set, the obligatory levels tool for setting black and white point (including ink droppers), a gamma control tool, and a functional curves tool. In addition to manual control of the curve, the curves tool includes some presets for dealing with over-exposed, under-exposed or low contrast images. All of these tools are perfectly functional and provide little surprise to those accustomed to image editing software. As with imaging editing software, they will not however be able to rescue images for which the colour or exposure data coming from the scan head represents poorly the original being scanned.

Fig 2. All 100% crops, unsharpened of the same slide (except the 10D image). Top Left: Scan using 4200F and Canon supplied ScanGear CS. Top Right: 4200F using Vuescan with a single pass. Bottom Left: Fuji Frontier film scanner. Bottom Right: Digital capture with Canon EOS 10D.

Capabilities
It is a widely known and easily defined fact that no flatbed scanner will be able to match the scanning quality of a dedicated film scanner, even high end hybrids costing three times the price of the 4200F are unable to match the outright sharpness, colour accuracy and ability to resolve shadow/highlight detail. The question here is to what degree this particular flatbed scanner can be used for scanning film, and if, for someone on a budget it is a viable solution within it's limits? If you seek high quality, high accuracy scans from film then you should already know that a dedicated film scanner is your only option. If you also need a flatbed scanner for prints and/or documents then you will need to buy a separate scanner. But what if you do not have the budget, or desk space for two scanners? Maybe one unit can do the job to a degree that is acceptable. Well, I suggest you define your level of acceptability and decide if the images from the 4200F shown in Fig 2 reach that level.

There are eight areas where we can look to differentiate between the quality of scanners. Software is one of them, as detailed above the scanning software supplied with this unit is perfectly acceptable for this level of scanner. The next is speed, again although the lightening preview times of 2.6 seconds do not apply to film scanning, the performance is acceptable. Defect correction is the next, and this scanner provides some basics, not bad for the money. The previous three are all what we would expect when paying for what is a budget scanner, the next five truly determine whether the scans are useable or not.

Resolution
Resolution is a term used and abused in an increasing manner. It is the shining jewel in many a promotional blurb. As with digital cameras and their megapixel count it is touted as the true indicator of quality. In both scanning terms (dpi) and digital cameras (megapixels) it means little more than the size the image will be, whether on screen or printed. Once the scanning resolution hits a point at which it can produce quality printed results, it becomes infinitely more important to consider other factors in the design. This scanner is already at the scanning resolution required to print 15"x10" prints at 300dpi - pretty acceptable for most people. The problem comes from the fact that the optical quality just can't recreate the original - at any size - with close accuracy.

Sharpness
If resolution is the fourth of a our quality criteria, sharpness is the fifth. Yes they can be linked, but again at 3200 dpi we are more concerned with sharpness from the optics rather than the scan head. The 4200F has a fixed focus system so it is always assuming that the point of focus (the surface of the film) is at a fixed distance from the sensing hardware. In reality, slides in the FAU are approximately 2mm from the platen, negatives 1mm and objects placed on the platen 0mm. These may seem like small distances, but consider than even in a focusing dedicated film scanner the curvature of the film can cause focus issues. The bottom line here is that the 4200F produces soft scans - maybe no worse than other budget hybrids but certainly not as sharp as a high end hybrid and not in the same league as a dedicated film scanner. The ScanGear CS unsharp mask option seems to have no effect on this, indeed the only thing it sharpens is the noise. Even bringing the images into Photoshop and carefully sharpening using your favorite tools will fail to bring the image to an acceptable level of sharpness for a 6"x4" print. The only output medium that will not be affected by the softness of the scans is an image for the web or email, where the dimensions prevent the softness (or extreme sharpening) from being noticeable. Fig 2 clearly shows this problem and compared to the results from a Fuji Frontier scanner, the likes of which any local minilab can produce, the 4200F has serious sharpness flaws.

Colour Accuracy
Our final criteria is colour accuracy. If you are a photo enthusiast then you probably select your films on their colour rendition amongst other things, so capturing those colours when converting to a digital format will be in your interests. The 4200F comes supplied with 3 ICC profiles (which can be a little hard to find if you are looking for them for use in other software - they are located in a hidden folder called "CanoScan" in the C: root - at great annoyance to myself. Why can't this folder be located in the correct place?) and the user can select in the "Preferences" dialogue whether ScanGear CS automatically chooses which one to use or manually choose any profile on the system. Unfortunately none of these options are going to do you much good, the colour accuracy is at it's best when letting the software select the profile automatically. This is not rocket science, the three profiles consist of one for reflective, one for negative and one for positive scanning - the automatic feature selecting the profile dependant on which media you have instructed to scan. I am not saying that the colour rendition is terrible, it isn't and is perfectly acceptable, so long as you are not expecting to recognise the Velvia hues that you see in the slide without considerable work in image editing software. The likely result is that your Velvia will end up looking like highly saturated Kodak Gold.

Density Range
The actual Dmin and Dmax figures for the 4200F do not seem to be published. A high density range is the stronghold of the dedicated film scanners and enables them to resolve detail in the shadows and highlights that lesser scanners just cannot pick out. The latest generation of top end hybrid scanners claim a Dmax of 3.8 upwards which is getting closer to the dedicated models, but a lack of claims for the 4200F lead me to believe it is not worth shouting about. In practice this seems to be the case. Once again what we are looking at here is getting for what you paid - and I doubt anyone considering this scanner will expect a high capability in resolving detail at the extremes of the tonal range. I certainly do not regard the 4200F performance in this respect to be bad at all - quite acceptable, and the lowest importance criteria in the company of sharpness and colour accuracy.

Fig 3. Left: Slide scan with 4200F and ScanGear CS. Right: Same slide, Fuji Frontier film scanner. Density range on the Canon is acceptable, and sharpness is the limiting factor in all cases.

Noise
Of the many causes of noise the one which is most relevant here is the noise produced from amplifying the signal from the scan head. This is at it's worst when trying to lift an under-exposed shot, and when attempting to resolve shadow detail. To make matters worse, noise is especially noticeable in dark areas of images. This problem affects all digital imaging sensors, and the reduction of it is a combined effort of higher quality sensor hardware and software, which leads to higher costs. So then, for a budget model we are expecting to see noise, and the 4200F produces exactly the amount of noise we would expect from a budget model. The machine does not offer multi-sampling scanning (that would be extraordinary), so noise in the shadows is apparent when viewing at anything approaching full size. However, the noise is lost in the noise (sic) when the image is output to print at regular sizes. One word of warning, the ScanGear CS unsharp mask feature will emphasise the noise terribly, leave sharpening to more dedicated tools.

Vuescan
In an attempt to try and drag more out of the 4200F, I moved the supplied software to one side and opened up Vuescan (8.1.22). Vuescan is third party scanning software for scanning geeks. Essentially it removes any control that Canon thought they had over their scanner with their software, bypassing it completely and reading the raw data direct from the scanning head. From there it can use it's own internal algorithms to convert the scan data to image data. The advantages here can be slender - and you will have to spend more time understanding the software if you want to eek out that last drop of quality.

Fig 4. Left: Single pass scan from 4200F with Vuescan. Right: The same with 8 passes. Notice that noise has successfully be reduced at the cost of sharpness. This is the result of inaccuracies in the scan head control between passes.

Apart from the almost infinite adjustments you can make in Vuescan to colour rendition etc., there are a few which should offer immediate improvements from the Canon software. Vuescan allows you to multi-pass the image, the theory (and practice) being that as a great deal of noise is random, so that a number of scans will allow software to recognise what is changing in each pass and call it noise. From there it can reduce it. In the case of muli-pass scanning with the 4200F it is indeed successful in reducing noise - but at a cost. Scanners which offer multi-pass ability require extremely accurate motor controls in order to scan the exact same point on each pass; the result if they do not is blurring. As can be seen in the crops of Fig 4, the 4200F does not quite have the control to pull off multi-pass scanning without a loss in sharpness, which is the last thing it needs. Multi-pass scanning may also have the added benefit of brining out detail in the shadows, as there is less noise from the scanning and exposure can be bumped slightly in a pass. I did not notice any particular gain in shadow detail from multi-pass scanning with the 4200F, other than that gained purely from reducing the noise. This suggests that the Canon software is already extracting most of the image detail the scanner can produce.

Vuescan provides complete control over colour management and rendition from the scanner. However, without any real notion of how to map image data to a colour space Vuescan stands little chance of producing accurate results. As stated before, Canon supply three ICC profiles with the scanner, and once discovered I instructed Vuescan to use the relevant one for the film type I was using. This appeared to make absolutely no difference at all - it could be that the ICC profile was not in a format Vuescan could read. One way to circumnavigate this problem, is to assign the correct Canon profile to the scan after it has been imported into Photoshop or other colour management savvy software. This at least gets you to the point of getting colour accuracy to within the level of the ScanGear CS software. Another possible area of gain is to scan a clear section of the film and store the data about the film terms, which can then be used to better interpret the scans of images from that film type. This improves things very slightly, but the basic problem we come back to is that Vuescan needs to be able to map the data correctly. The solution - purchase an IT8 target and use that to create a complete profile for the scanner. This will give Vuescan the insight it needs into how the scanner is reporting hues and be able to map them accurately into you chosen colour space.

To summarise Vuescan's ability to increase performance of the 4200F, it can do very little to improve colour accuracy; without creating a custom IT8 profile for your scanner. It can reduce noise in shadows with multi-pass, but at the same time decreasing sharpness, which is the weakest link already - and an area in which Vuescan can make no improvement. ScanGear CS is quicker, simpler and once you have the image in your image editing software you can apply any colour corrections that VueScan could offer.

Conclusion
As clearly stated, I am only concerned here with the CanoScan 4200F's abilities to produce scans from a film source, for someone who wishes to maintain the original colours of the image and desires to display or print them at higher resolutions than would be needed for a web graphic. From this point of view the 4200F acts as little more than a digital lightbox - and that can be useful in itself. It is reasonably fast which means that preview images can be viewed quickly and composition and exposure evaluated, taking "keeper" shots to your local lab to have them scanned on a dedicated scanner.

If you wish to maintain control over your workflow and wish to do the scanning yourself, them I am afraid that you are going to have to spend the bigger money on a more accomplished scanner. It maybe tempting to look towards a higher specification hybrid, I am not sure this is the wisest option. A "good" hybrid scanner that improves on the performance of the 4200F is going to cost you considerably more, in fact not too far away from a very respectable dedicated film scanner. A wiser option would be do buy the dedicated film scanner and a budget level flatbed - if you really need the flatbed capabilities. Overall you will not be spending a great deal more money than a high end hybrid, but you will be getting quality film scans and document scanning when its needed.