Ah, I misunderstood. You were talking about F-stops, so I thought you had changed something on your main camera. So are you doing a HDR lit only testing or are you using a Poser light (like an inf)? Doesn't sound like it though. Environment sphere settings then?

"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