Framing shutter - who is setting the bounderys


i once again wondered about the framing shutter controll.

If i turn the angel of a blade, at some point it is reaching the limit of how it can be moved with the trust.

Thats what the desk is suggesting me.

But how does the desk know?

New fixtures are designed to do crazy things with there blades...

Is the boundery, the desk suggestes me, the real one?

I can't believe this.

Any thoughts?