When Canon announced the 5D back in 2005, it was a game-changer. The
camera was the first full-frame DSLR--meaning that its CMOS sensor is
the same size as a frame of 35mm film, about 60 percent larger than the
sensors in most DSLRs--in a standard sized SLR body, all for just a bit
more than $3,000. Three years later, its successor, the 5D Mark II,
pushes the image-quality bar higher and the cost of entry lower.