Archived posting to the Leica Users Group, 2001/07/24
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> From: Austin Franklin [mailto:darkroom@ix.netcom.com] > > > The recent POP Photo scanner review *measured* the resolution of > > the LS-4000 at 60 lp/mm. As I understand it, noise plays a major > > role in reducing the true resolution of a scanner down from the > > theoretical resolution (which would be 78 lp/mm for a 4000 SPI > > sensor). > > I'd have to think about that, but that does not make sense > (noise limiting > the resolution) to me. Noise certainly does limit the > dynamic range (which > is on a per pixel basis), but I fail to see how it limits the > resolution, > which would be across pixels. If the lense is not up to snuff, or the > scanner has vibration issues, I can see that limiting > resolution...but not > noise. I agree that electrical noise in the CCD would reduce dynamic range, not resolution. Something is lowering the resolution, though (if Pop Photo is to be believed :-) Could one culprit be the scanning lens itself? After all, the light doesn't go straight from the LED to the sensor. What about scattering in the film and emulsion itself? And bloom, and vibration. In all liklihood there are a large number of factors contributing to the degradation, just like there are with any other real-world process. All that aside, 60 lp/mm at the scanner is still OK for me - it will make 11x14's that look just fine (at 360 dpi to the printer and 5.5 lp/mm on the print. Paul