Erm, can I ask why you'd want a shadow blur to be 20? I'm looking around my rec room right now lit by a flourescent light and I guesstimate the blur to be no more than a 5. Is the only light for your scene coming from the window? I usually use a shadow blur of 3 or 4 and put my samples at 50 to 70 on each light.

"A lonely climber walks a tightrope to where dreams are born and never die!" - Billy Thorpe, song: Edge of Madness, album: East of Eden's Gate

Weapons of choice:

Poser Pro 2012, SR2, Paintshop Pro 8