As a minimum, the UCSC Library Digital Initiatives department scans materials according to the Technical Guidelines for Digitizing Cultural Heritage Materials
Master files are nearly always TIFF files scanned with the following settings: 16-bit depth, Adobe 1998 ProPhoto color space, color mode.
Scanning resolution varies depending on the format and size of the original material.
See the Technical Guidelines for more details.
What do these standards mean to those of us who'd like to enlarge and print a digital file? Using this handy page that helps calculate printed images sizes based on dpi and the screen or printer resolution, here are some general guidelines:
Note that reproduction prints from negatives and slides are generally much better quality. For more information about printing resolutions, consult your publisher, printer or production artist.