orthographic yafray render producing artefacts

Hi there,

I’m having a problem with rendering an orthographic view with yafray. look at this perspective rendering

http://www.lastfuture.de/temp/gehirn.png

and then at this one with the camera switched to orthographic but no other settings changed

http://www.lastfuture.de/temp/brain_effed.png

I get those artefacts with every render but each time they’re distributed differently across the edges of the object. It definitely looks like a bug and only seems to affect the faces that would usually be invisible to the camera in non-orthographic view.

Is this a known problem with a fix? any way to work around this?
I’m using blender 245

– Peter