What's it useful for?
I use my scanner mainly for photocopying, but I also want to archive all my old transparencies and photos in digital form. I will therefore specifically comment about these two uses, both of which the CanoScan 4200F handles well. My old
Epson scanner broke, and the main improvements I was looking for in the replacement were build quality, quietness and speed, so I will discuss these aspects as well. Other useful features are optical character recognition, scan to PDF and scan to e-mail.
Overall design
The case is compact, rigid and attractive, and the buttons give a solid click when pressed. The lid has two hinges that allow it to accommodate a thick book. The lid is not detachable and the hinges are metal and seem robust. Only time will tell whether this scanner will outlast my previous ones, but it has been reliable so far. A separate light is built into the lid for scanning transparencies and film negatives, which should give better results than cheaper adapters that reflect light up from below and back down again. A slightly flimsy but adequate white plastic backing sheet slides into the lid when doing normal flatbed scans.
The holder for transparencies and film is a little fiddly to use, clipping into the lid rather than sitting on the glass platen, as with my old scanner. This means that to change transparencies you have to open the lid, unclip the holder from the lid, unclip the transparencies from the holder, insert the new ones and clip it all back together again. The holder also takes only two transparencies, which seems an unnecessary restriction. My previous scanner took four without trouble, and changing slides was much quicker. However, the Canon arrangement does hold everything in place more securely, which means better alignment and noticeably more accurate automatic cropping of images. Note that more expensive scanners in the Canon range such as the 8400F can scan 12 transparencies at once.
Noise
This is the quietest scanner I have heard, which is very welcome and is a good sign for reliability, inasmuch as fast-wearing mechanisms tend to be noisy. There's an option in Advanced Settings/Preferences/Scanner to enable a "Quiet Mode", which seems to work simply by reducing the motor speed when retracting the scan head at the end of a scan or during a fast preview. It's quite effective and only adds about two seconds to the scan time, so it's a useful option.
Speed
On paper, the CanoScan 4200F appears faster than most of the competition - only 2.5ms/line at 800dpi compared with around 10ms/line for most other scanners, even including other Canon models, according to www.canon-europe.com. Indeed, a full-page preview scan does take only 2.6s! (Quiet mode doubles this.) In practice, the long warm-up time of this scanner makes the first scan frustratingly slow, but subsquent scans are indeed fast.
The design of the software drivers is also important, because unnecessary prescanning or waiting for the lamp to warm up can greatly increase scan times. And there's no point scanning quickly mechanically if the USB connection to the computer can't keep up. None of the reviews I have seen really address this point so I had to buy the scanner to find out! The results I measured are discussed below - fortunately, the software is also quite fast.
Photocopying
The quality of copies printed direct to a (colour laser) printer just by pressing the COPY button was generally excellent, without any need to "tweak" the driver settings or do multiple scans to adjust brightness or contrast. This in itself saves a lot of time. There's also a neat "multiscan" feature that automatically detects multiple photographs placed anywhere on the platen, crops them and processes them separately, another time-saver.
If necessary, all the usual manual controls are available, to adjust resolution, brightness and contrast, colour, gamma correction, histograms and tone curves. There are also filters for Descreen, Unsharp Mask, Reduce Dust and Scratches, Fading Correction, Grain Correction, Quality calibration and Auto Exposure, of which only Unsharp Mask and Auto Exposure are enabled by default. Additional postscan processing, for example to remove "red-eye", can be done with the supplied ArcSoft PhotoStudio software, which I found basic but adequate. All the software was quite easy to use and bug-free.
I tested copying times using a USB2 connection to an Athlon 2200+ PC with 512MB of RAM running Windows 2000. Times quoted exclude the time to position the original on the platen, and printing times.
The first copy was very slow, around 1 min 40s in "auto" mode (simply pressing the COPY button), before anything is sent to the printer. This long warm-up is quite frustrating and is my main complaint about this scanner. Once warm though, subsequent copies take only about 23s in auto mode or 16s in manual mode. By "manual mode" I mean clicking with the mouse on the scan button in the copy dialogue on screen, with "Platen, Color, Standard, 100%" already selected. This is excellent, about twice as fast as my old scanner. Although it is still somewhat slower than a "real" photocopier, it is quite acceptable because if the scans were any faster, copying speed would be limited by the USB2 connection, the printer, or the time to position the original document anyway. And unlike most photocopiers, multiple copies of a single document can be made without rescanning the original, which can save a lot of time if you have a fast printer. And they're in colour!
So, my conclusion here is that at last I've found a scanner that can easily make multiple colour photocopies, but the initial warm-up time when making a single copy is a problem. More expensive scanners in this range do warm up faster (the 8400F claims 20s).
Archiving transparencies and photographs
I was very interested to see if it was really practical to use this scanner for archiving transparencies, film negatives and photographs. The alternatives are sending them all off to be scanned professionally, or buying a dedicated film scanner, both relatively expensive options. In theory, the high colour depth (48 bits) and optical resolution (3200dpi) of this scanner should be sufficient for archiving, so I did some trials to see how practical it really would be. Would the quality be sufficient, and how much time and storage space would it take?
The whole point of archiving is to capture all the information in the original, but I knew some compromises would be needed, because uncompressed, high-resolution scans take up a great deal of space. By default, the scanner driver adjusts the scan resolution to match the intended output (an A4 print, for example), but I didn't want to make this assumption for archiving. I compared zoomed-in details of scanned images with a conventional image projected on a full-size screen and looked for loss of detail or colour.
The first surprise came when I tried to use 48 bit colour depth. First, you have to select "Use the Scanner Driver to Make Advanced Settings", then press Scan and select Advanced Settings/Settings/Preferences/Scan/Enable 48/16 bit output. A new option "Color(48bit)" then appears in the Main/Color Mode dropdown. If you select this and perform a scan, you get a warning "The image cannot be transferred if the application does not support 48-bit color...", and for good reason. The CanoScan Toolbox itself (the application launched by button presses) does not support it! Nor, I discover, do most display drivers, printer drivers or compression formats. I did manage to scan a transparency directly into the supplied ArcSoft PhotoStudio at 48 bits and the maximum 3200 dpi resolution, and save it as a 70 MB TIFF file or a 14 MB PhotoStudio file (taking 30s for the prescan and 50s for the full scan). But I have no way to view or print the full 48 bit colour depth output so I don't know if it's worth it.
At the default (24 bit) colour depth, a 3200 dpi transparency scan occupies about 34 MB saved as a lossless TIF, but only about 1 MB saved as a high '90' quality JPEG. That's comparable to the space taken by pictures I get from my digital camera, which suggests it contains about the right amount of information. Interestingly, it takes about the same time as the 48 bit scan, which suggests that the speed of the USB2 connection is not a limiting factor. Comparing the scan with a projected image on a full-size screen, the amount of detail appears similar - the film grain is just visible. The colour depth was also very good, with good detail in shadows.
Note that the default resolution in fully automatic mode appears to be only 1600 dpi, which compresses to around 370 KB - definitely a loss of information there! Fine for printing, but not for archiving. Even with the the best image quality, "Enlarged printing (600dpi)" selected in the default scan dialogue, I could see significant loss of detail compared with the full-size image. You have to go to Advanced Mode and select 3200 dpi to get the full benefit of this scanner's resolution when scanning transparencies or film.
Checking for excessive cropping at the edges, I could see no significant loss. A manual cropping mode is available - confusingly, you have to click a button to enable "thumbnails view" to get it - and there's an option under settings/preferences/preview to disable automatic cropping, but I didn't find this necessary, automatic mode was fine.
As I mentioned above, the Unsharp Mask and Auto Exposure filters are enabled by default. My first instinct was to disable them for archiving, since they may remove information and they can always be applied later if necessary. On the other hand, they are both quite subtle and they do definitely improve the scanned image. It could be argued that they are merely compensating for imperfections in the photography and scanning process, and so restoring the images to a more faithful representation. If you are a photography enthusiast with the time to adjust each image you will probably want to disable the filters, otherwise most people should probably accept the default. There are sample scans at http://mckerracher.org/canoscan4200f so you can compare the results. There are also "Fading Correction" and "Grain Correction" options, both of which I find much too severe even on the Low setting, and leave deselected.
For dust removal, I find a simple blower brush, available cheaply from most camera shops, is the most effective solution. More expensive scanners in the Canon range claim to compensate for dust and scratches automatically using infrared "FARE" technology, but I'm skeptical. My scanner had visible fingerprints and smudges on the glass platen when I received it, easily removed with ordinary window cleaner.
The software drivers include some useful options to help with cataloging. Pictures can be saved with a default filename, to which a numeric suffix is automatically added if necessary, intelligently avoiding any numbers that have already been used in that folder. If you make this name the year the picture was taken and scan your oldest pictures first, your pictures will sort chronologically by filename. There's also an option to set the EXIF information as each picture is scanned, which allows you to record any information that may have been handwritten on the original transparency, for example. You can easily rotate and flip pictures to get the orientation right before they are saved. It's not possible to orient transparencies requiring a 90 degree rotation correctly before they are scanned due to the geometry of the holder.
Negative film strips can be scanned just as quickly and easily as transparencies, and generally give better results than scanning printed photographs.
So, here's a summary of the whole archiving procedure for transparencies and the time it takes:
1. Unclip the transparency holder from the lid, open it, remove previous transparencies and insert two new ones to be scanned. Blow away dust and clip it all back together. This takes me about 40 seconds.
2. Make sure "Use the Scanner Driver to Make Advanced Settings" is selected and adjust the file name if necessary, then press "Scan" to start a prescan. Takes about 35 seconds if warm, two minutes if not.
3. Rotate images if necessary, select all images, check that Advanced Mode/Main/Output Resolution/3200 dpi is selected, press "Scan". Takes about 50s per picture.
4. Edit the EXIF information if desired and press "Save". Alternatively, save immediately and then edit the filename to describe the picture while the next one is scanning.
It will therefore take about 3 minutes to scan each pair of pictures, or about 40 pictures per hour. If you have hundreds of pictures it's going to take days to scan them all, so you will probably want to do it as a background activity while you do other things.
Scanning documents
Documents can be scanned direct to PDF format, with the option of making the text "searchable" - in other words, optical character recognition has been performed but the document looks exactly like the original. I found this worked surprisingly well in practice. A 300 dpi colour scan takes about 15s and occupies about 1 MB of disc space (or 200 KB with "high" compression selected). A 200 dpi greyscale scan (fax quality) takes about half that time and space. Multiple pages can be scanned into one PDF file. It doesn't seem to be possible to edit the PDF properties with the supplied software.
Optical character recognition using the supplied Caere OmniPage Pro 9.0 software was a big disappointment, though. Most of the printed text was recognised correctly, but proof-reading and fixing the resulting errors takes a long time, and the output page layout was a complete mess, even on simple pages. Don't plan on using this for anything serious.
Update
Note that the scanning slot in the transparency holder is 24mm wide, which is fine for modern 35mm transparencies and negatives, but older "square" formats may be cropped a little in one direction.
