Thanks Don Franscesco and tcook!
Don, it is not so easy to preserve some detail with such reflecting surfaces.
I had to test four different setups.
Francesco, the shadow-free ringlight is just a focussing aid for me - in most cases.
You need several ringlights for specific distances and there is still no shadow...
My modified heads of torch lights can be adjusted and give a better light (F:8.0; t:1/30sec). There are stronger LEDs like Luxeon, but living animals don't like such strong lights. They have some reasons to stay in the dark.