Information about scanning 35mm slides at 2000 dpi and 4000 dpi

fuji 200 slide
fuji 200 scan from slide


35mm images
A 35mm image has a width to height ratio of 3 : 2 ( approximately 1.42 inches wide x 0.95 inches high )

2000 dpi VS 4000 dpi
When a slide is scanned at 2000 or 4000 dpi, the number of 'dots' created when scanning the width of a slide is:
    2000 dpi x 1.42 inches = 2840 dots wide
    4000 dpi x 1.42 inches = 5680 dots wide

When printed on a printer at 300 dpi, the printed image width would be:
    2840 dots / 300 dpi = 9.5 inches wide
    5680 dots / 300 dpi = 18.9 inches wide

Which should I select - 2000 dpi or 4000 dpi?
1. Images that need to be blown up for poster sized printing and that need fine details displayed should be scanned at 4000 dpi.
2. Images that will be used for 'intensive' color balance work and cropping/editing may benefit from being scanned at 4000 dpi. (i.e. experienced Photoshop users may want 4000 dpi scans)
3. Images that do not need to be increased greatly in size, will be edited by inexperienced Photoshop users, or that will only be displayed on web pages may be scanned at 2000 dpi.
4. Images the will be sent to an online printing site like Ofoto or EZPrints for prints as large as 11 x 14 can be scanned at 2000 dpi.

Examples of 2000 dpi and 4000 dpi scanned images
The above image of a barn will be displayed below in three different ways:
   - approximate size of the slide
   - section of barn when scanned at 2000 dpi
   - section of barn when scanned at 4000 dpi

Note that 4000 dpi scans are desirable when you want to enlarge the original image (the slide) many times...


approximate slide size
Approximate 35mm slide size


original slide size
Size when scanned at 2000 dpi (cropped to fit screen)


original slide size
Size when scanned at 4000 dpi (cropped to fit screen)