Canon's CanoScan FS4000

Version 1.2, Page 3, ©2001 by Dale Cotton, all rights reserved

Colour and Tonal Gradations, continued

Slide film (New Sep 15, 2000)

I discussed tonal gradation above. We can think of Dmax as the degree to which subtle gradations in colour are captured in the dark extremes. Whether we see a black cat lurking in a tree shadow or not depends on whether we can distinguish between charcoal grey and inky black.

Because transparency film is significantly thicker than neg film, scanners have a greater challenge extracting the charcoal greys from the true blacks. Although I no longer shoot slide film, I have many boxes of slides to re-scan left over from my "student" days. I decided to investigate for myself whether the FS4000 has noticeably better Dmax than my previous S20 scanner, and if so, whether it has enough to salvage some of my more problematic slides. Here's the image I decided to use for this test:

Figure 4. Normal exposure vs. Figure 5. +2 exposure. (Warning: clicking opens 400+ KB files.)

Figure 4 was done using the FS4000's 0, or normal, exposure setting; we can see that it is about a half stop underexposed - great for the sky but problematic everywhere else. Figure 5 shows the same slide re-scanned with the +2 setting. +2 increases the lamp brightness to maximum, digging deeper into shadows with the side effect of washing out light regions of a scan.