Another way that drum scanners are different than flatbeds, minilab scanners and virtual drum scanners (like the Hasselblad Flextight’s), is that they illuminate the film at a single point throughout the scanning process. This ensures there is no bleeding between bright sections of the image into the darker areas, increasing the amount of detail in the shadows.

Example 1: 4x5 Velvia 100

Drum Scan of 4x5 Velvia 100 Slide

Drum Scan - Howtek 4500 Shadow Detail - click for full res

Notice how much more shadow detail the above scan is able to produce. The flatbed below hides a lot of the detail in the darker rocks. Even if you applied an adjustment to the flatbed scan, it would mostly be noise, hiding detail.

Epson Flatbed shadow detail - click for full res

Example 2: Severely underexposed Velvia 100 4x5”

Velvia scan before adjustments

Velvia scan after adjustments

Example 3: Underexposed Kodachrome 35mm Slide

Kodakchrome scan before adjustments

Kodachrome scan after adjustments