rendering with a light, effecting no DIffuse, but making shadows only

[caypiranha]

Hi Guys,

How is it possible to render Light´s Shodow only, without affecting any radiance/lightpower affecting the rest of the Objects?

On this, I had a look at the Vray Properties of a light keeping the "Generate diffuse" Properties with the Diffuse Subdivs and multiplier options - but how i use them?
dont see any effect on them and cant find anything in the help

Thnx! - kay