Okay, my math is a bit rusty - the Nikkor 90mm (any brand, really - it's just a size conversion for format) on 4x5 is roughly equivelant to a 28-30mm for 35mm film (in a nutshel, divide by 3? - a 150 is basically normal length for 4x5). Which would roughly be somewhere in he vicinity of a 17-20mm lens for an APS-C sized digital sensor?

That sound about right?