Yes, thank you for the answer, I have done it that way, after I figured it out myself. Thanx anyway!
But the iris is still a problem. I do not really know exactly how the parts of the iris have to look like. The shape I created and duplicated seems to be ok. but when you look closer, the surfaces intersect, and I do not know how to get the correct shape that avoids this problem. Does anyone have a scheme of the iris???

Best Regards

Markuz