AF lens - construction

[oldfauser]

How many AF Nikkors are constructed like the AF 180mm f/2.8 ED-IF and the 300mm f4 ED-IF?  Both have no internal AF motor, screwdriver drive, with a AF switch to disconnect the manual focus ring (keeps it from not turning during AF operation), not like say the 50mm f/1.4 AF-D where the the focus ring turns...  I can only find these two lens constructed like this.  Reason I'm asking is longevity of the AF function; the 80-200mm f/2.8 AF and those with internal AF motors seem to be failing, rendering them a manual focus lens as the parts to repair them are getting to be in short supply!

Art

[Roland Vink]

The AF 180/2.8 and AF 300/4 are the only two Nikon lenses which have the switch on the focus ring to disconnect it. On all other screwdriver AF lenses the focus ring either turns during AF (eg 24/2.8, 35/2, 50/1.4, 85/1.8 ), or there is a separate A-M ring on the lens barrel for connecting the focus ring (eg 85/1.4, 105DC, 135DC, 60/2.8 micro, 105/2.8 micro, 200/4 micro)

The small switch for AF/MF on the side of the barrel did not appear until AFS lenses.

In terms of longevity, the older screwdriver AF lenses are simpler so there is less to go wrong, but nothing lasts forever. The A-M rings are known to crack and split which requires an expensive repair, and other mechanical parts do wear out. Even solid manual lenses get oil on the aperture blades, the grease in the focus ring dries up, glass accumulates dust and fungus...