LaserSoft Imaging

Silverfast 6 for the Nikon Coolscan 4000 allows a maximum resolution of 8000dpi while the Nikon scanner has a max optical resolution of 4000. I assume that the higher number is an interpolated resolution, doubling the "real" resolution in software. For this reason I have never used is, assuming that it would result in inferior scans. The other day I tried the 8000 setting and (while the scan time was extremely long - about 4 minutes) I got an excellent quality file of about 220MB. I could not find any info about this setting in your manuals and wonder if someone can explain to me what is behind this. Does SF recommend the 8000 setting, was it tested? I have seen no deterioration in quality, also after downsampling the file to 4000 dpi and comparing it with a scan made at 4000 I see the same sharpness and no artifacts. If this is true it would add a valuable feature to the Nikon scan by doubing the maximum resolution. Any comments are welcome
Thanks
Thomas

Dear Thomash.

You are right. The LS4000 has an optical resolution of 4000 dpi and SilverFast always offers the double of the optical resolution as the maximum resolution for scanning. At resolutions above the optical resolution of the scanner, SilverFast performs the scan with the optical resolution and interpolates up. You are also right in assuming that the qualtity can?t be better than scanning with the optical resolution. There is simply not enough data to enhance the qualtiy. If you are satisfied with the quality of 8000 dpi, then that is just good, but the quality won?t be better compared to 4000 dpi. Scanning with 8000 dpi can be usefull, if you want to print large images, like posters.

Best regards
Eric.

Hi,

interesting discussion indeed.
I have recently started scanning with a Nikon 5000ED and also found that it makes a difference whether you scan with 4000 dpi (max optical resolution) or with 8000 dpi. I understand that 8000 is good for big prints but why does a 8000 dpi give a sharper image on the screen (24' LCD)?? The difference is really vissible. Of course I would prefer a 4000 dpi scan because of the file size (250 MB vs 50 MB) but on the other hand I don't want to loose any information from the source document (slide).

Any advice is much appreciated
Silvertor

What you are probably seeing is aliasing generated by scanning past the nyquist frequency of the optical system and the image itself on the film. The 5000, in my experience, can only resolve about 3300-3500 ppi. Anything above that is "made up" information. It can give the appearance of a sharper image but the "data" was not in the film image. A drum scanner scan can get into that range, but it may be beyond what the film image contains depending on the lens, film used, and processing.

Frank