Here's an example of the amount of detail available in a 4x5 slide.   This sample was only scanned at 1500 dpi, so it probably only captures 10% of the available information in the slide (assuming there is approximately 5000 dpi of information on the slide).

The original scan is 7050x5425 pixels, which would equate to a "38 megapixel" digital camera.  At 3000 dpi, it would equate to a "150 megapixel" digital camera!!  Try storing a few of those 450 MB TIFF files (ie - 24 bit color) on compact flash!!  Hi-res 4x5 scans make great prints up to 40"x50", so are great for dramatic landscapes.

Anyway, below are the reduced original and the full 1500 dpi zoomed section...

Reduced 7050x5425 Scan

Actual Pixels from same 1500 dpi scan