Manual Focus Lens question.

[Kronos]

Probably a stupid question, but:

When you look at most Nikon manual focus lenses they have this metal thing that sticks up between the F-stop ring and the ADR ring. What is that thing for and what purpose does it serve?

[JoePhoto]

They're called rabbit ears - they are a meter coupling shoe that allowed the lens to communicate it's f-stop to the older meters by adjusting a lever when the aperture dial is rotated. My Nikon F and it's lenses have this.