I recently experienced something weird on my renderings that I can’t understand and solve.
The shadows on it look “wavy”. I’ve tested the following points but it does not the trick… Any help would be warmly welcomed!
tests :
See the BPR result after.
Thank you for your attention 
Hey. Also try changing the shadow resolution slider. I have to be at 4096 or above to get shadows with no artifacts. The shadows were great in Z4, then went bad with Z42, and are now almost back to where they were in Z4. I usually start with rays around 90, and angles below 1.5, and gradually dial the angle settings up or down. Hope this helps.
Thank you for your answer mister Carver. I will try your settings soon. By the way I must tell you that I really enjoyed your work on the Brigestone balls and appreciated the tutorial you provided recently. Good job ! 