OK. So some lenses have 5 pins, some have 7, some 8, some 10. I understand that 9 and 10 are used to talk to a teleconverter so that it reports the "adjusted" focal length and F/Stops to the camera. I also know that pin 8 is used to provide an additional high current ground on some lenses, I "think" in particular larger lenses with the bigger AF motors in them.

My question concerns pin 8. I have a set of Kenko extension tubes. They have 7 pins of pass-through, so pin 8 is not connected. Therefore the lens is not getting its "extra ground". Any Nikon engineers out there that can tell me what what kind of effect this could potentially have on a lens that is expecting pin 8 to be connected? Will insufficient grounding shorten the AF motors' life, etc?

The following lenses I have all have 8 or 10 pins, but that doesn't necessarily mean that pin 8 is being used.

16-35 F/4 AF-S VR
24 F/3.5 PC-E ( manual focus so probably doesn't matter here )
50 F/1.4G
70-200/2.8 AF-S VR1
85 F/2.8 PC-E ( manual focus so probably doesn't matter here )
200 F/2.0 AF-S VR1