This frame cost 4 and half a hour to render. The depth of field effect performs nicely however I do not possess enough time to continue this efficiency. I had better to render rpf files with z depth so that I can apply this effect in After Effects.

This is the same frame using Frischluft Lenscare and additionally added glow to the metal melt. As a matter of fact it might sacrifice some detail comparing the image made by previous way. On the other hand, this is the best solution considering the balance between quality and efficiency. What's more a video requires less image standard than an still picture.