This is the data accompanying one of my photos on Wikimedia Commons
Camera manufacturer FUJIFILM
Camera model FinePix2800ZOOM
F-number f/2.8
ISO speed rating 100
Date and time of data generation 18:14, 4 September 2010
Lens focal length 28.7 mm
Orientation Normal
Horizontal resolution 72 dpi
Vertical resolution 72 dpi
Software used Digital Camera FinePix2800ZOOM Ver7.00
File change date and time 18:14, 4 September 2010
Y and C positioning 2
Exposure Program Normal program
Exif version 2.1
Date and time of digitizing 18:14, 4 September 2010
Image compression mode 2
Shutter speed 7.1
Aperture 3
Brightness 5.38
Exposure bias 0
Maximum land aperture 3
Metering mode Pattern
Flash Flash did not fire
Color space sRGB
Focal plane X resolution 2,442
Focal plane Y resolution 2,442
Focal plane resolution unit 3
Sensing method One-chip color area sensor
Sharpness 3
White balance Auto white balance
Presumably there's similar data for every unedited photo. Wonder how difficult it would be to use it to acquire a database of people owning seriously expensive cameras, for spamming or more sinister purposes...
