[dave9t5]

Informative article here about onion-ring bokeh and it's cause by the lathe marks of the aspherical mold manufacturing process.  Also about the challenges of eliminating it and Panasonic's efforts with an example of the improved processing method being utilized in the Panasonic Leica Nocitron:

 

http://www.imaging-resource.com/news/201...ric-lenses

 

(Tangent: When will PZ test the Pana Leica Nocitron 45/1.2 ??)

 

The Samyang bokeh is a bit different, as Scythels points out, likely due to effects from the edges of the lens elements.