Hi,
I was playing around with Corona and did a rendertest with DoF activated. Deadclown told me to use a value of "4" for Path Tracing Samples instead of the default "16". I re-rendered the image and it got obvious that the daylight direction had changed. At first I thought i made some changes so I did a quick 5 min rendering with 16 samples again and one with 4 samples and the same "problem" occurs.
Sofware: Max 2k12, Win7.
I attached the max-file for you to test this out yourself or maybe tell me why this happens :)