LenScore™ Falloff
 
Most lens testing labs calculate falloff by simply comparing corner brightness to center brightness. That certainly is a quick and easy way of getting a general idea about a lens' vignetting performance, but it literally does not take into account the whole picture. Have a look at the following falloff patterns:

All of them have 2-stop vignetting when comparing corner to center brightness, but falloff performance is clearly not the same. The LenScore™ falloff score is based on 40 test images (f/1.4 to f/16 at 5 focusing distances) with 192 million falloff values calculated per image. It is a highly accurate measure of a lens' vignetting performance over a wide range of conditions and substantially more meaningful than a simple corner to center comparison.