Render mode, shades and silhouette

I am having problem with getting nice shades in rendered views. I adjust the shadow by going to edit rendered settings, shadows and than the camera based clipping bubble must be adjusted to show any shadow. The shades look very dirty, like rough pastel coloring. Also I would like to adjust the silhouette. When I use the clipping plane I think they are to thick.

Hei Sunna - could you attach a 3dm model and perhaps an image? Also, please run the Rhino SystemInfo command and copy-paste the result here.

Hi Wim
I wanted to attach the image in my first post but I couldn´t find the attachment button . I have attached a file before without any problemso I am not understanding why it dosen´t show up or maybe I need a good weekend vacation in the countryside. I will come back after the weekend to find the attachment button :).

Hi Sunna - the easiest is perhaps just to drag-n-drop things into the message.