I've been doing a bit of research on the Kodak RFS 3600 film scanner, and found out a few interesting things. It's actually made by Pacific Image Electronics, the same company that makes the PrimeFilm 1800u film scanner.  The RFS 3600 is apparently just the next generation of the PrimeFilm 1800u (note that 2 x 1800 is 3600 dpi).  If you compare the physical dimensions of these two scanners as well as the film feeding, you'll see the similarities (Kodak apparently added more plastic to the case to make it look fancier). When I first learned of the RFS 3600 I wondered why it was a 3600 dpi scanner and not a 4000 dpi scanner. It turns out that most film scanners use CCD chips that were originally designed for flatbed scanners (which is a much bigger market than film scanners), and most flatbed scanners are 8.5 inches wide.  A 300 dpi flatbed scanner needs a 2550 pixel CCD, a 600 dpi flatbed needs a 5100 pixel CCD, and a 1200 dpi flatbed needs a 10200 pixel CCD. Most 2700 dpi film scanners use the 2550 pixel CCD's, since this lets you scan 24mm wide film.  The Polaroid 4000 dpi scanner uses a 5100 pixel CCD (they could have designed it to go up to 5400 dpi, but I suspect they didn't because they didn't want to build a 5400 dpi stepper motor).  It appears that the Polaroid SprintScan 120 uses a 10200 pixel CCD (10200 pixels over 60 mm is about 4000 dpi). It appears that the PrimeFilm 1800u uses a 2550 pixel CCD, but this has to scan a 36mm width (because of the way the film is fed from left to right) but the scan head travels in the 24mm direction.  This means that the maximum dpi of the 2550 pixel CCD over a 36mm width is 1800 dpi. Similarly, the 5100 pixel CCD in the Kodak RFS 3600 spread over a 36mm width results in 3600 dpi. (5100 * 25.4 / 36 = 3598 dpi). The PrimeFilm 1800 uses parallel-port scanner firmware internally, and converts USB to parallel port commands internally (it's a huge kludge).  I suspect (but don't know for sure) that the Kodak RFS 3600 uses the same internal firmware as one of the PIE SCSI flatbed scanners, with an optional USB-SCSI converter chip. In summary, there appear to be mainly 3 sizes of CCD chips in use in film scanners today.  Most use 2550 pixel CCD's, the SprintScan 4000 uses a 5100 pixel CCD, and the SprintScan 120 uses a 10200 pixel CCD. Regards, Ed Hamrick http://www.hamrick.com/vsm.html