Can some explain this vignitting problem to me?

[driggett]

Would some explain this vignetting problem or point me to a link? Why does film not have this which is full frame and a digital sensor which is roughly the 2/3 the size in the middle do? Why do I not have this on my D2h and do on my Epson?
Thanks,
Chris

 

[Huck Finn]

www.luminous-landscape.com/reviews/lenses/rd-1-lens.shtml