[Brightcolours]

Native resolution for my old Epson V750: 6400×9600 dpi (So Epson says, but I'm nearly convinced it's only 6400 × 9600 pixels in total?). Size of the flatbed area: 8.5 × 11.7 inches. If my calculations are not totally off, I get 54.400 × 112.320 pixels = 6110 MP ? And it only needs 12V= and delivers via USB 2.0 or FireWire 400. I only need a big enough lens and a tight enough box. Oh, and the subject to "photograph" needs a bit of patience, a couple of minutes will do. It comes with 48 bit color and has a density range of 4.0 log D

Should do for my large scale sensor experiments. And that appartus then could be called as experimental.

The scanners work with (bright) internal light reflecting off the document, with that document plane being in focus on that plane obviously. The scanner focusses that plane onto the CMOS or CCD internally. To make photos with a scanner you need to do modifications. You need to turn off the light, and possibly modify parts that "focus" the light to the CCD/CMOS, to get rid of extreme vignetting.
Disabling the light often means that the scanner will not work with the standard software, which tests if the light works. 

Easier will be to use a pane of glass to which you stick special opaque projection foil. You focus the image on that foil, and the scanner will see that as if it is a piece of paper to scan and the normal scanner optics can remain untouched. You still will need to be able to turn off the light, though. So you may need to find an open source scanner software.