Spirea's Diablo II Resource

Magic Find

Since patch 1.09, magic find is now subjected to a diminishing return formula when the value is above 110%. The formula used is 
effective MF = 110 + a*(MF-110)/(MF+b)
a and b are variables as follows:
a b
Uniques 250 150
Sets 500 400
Rares 600 500
This calculator will compute the effective MF based on what was described above.

Magic Find %
Item type Effective magic find
Uniques %
Sets %
Rares %

Thanks to Jarulf for providing information.