The OP wasn't referencing older AF film lenses but MF models. The Nikon EM was a manual focus camera thus AF isn't relevant here. Plus some older Nikon DSLR's also had focus motors in the camera. Like the D50, D70/s (which I owned & gave to one of my sons), D200 & D300 (which I still have) as well as the D7xxx series cameras. The older lenses you are referencing are Pre-Ai (auto indexing) and will damage any Nikon DSLR with a built in focus motor (except for the Df). They will not damage the D3xxx or D5xxx (nor the older D40, D40x or D60) as those models don't have that built in focus motor. What happens is that the "aperture "skirt" extends down past the mount face & fouls the aperture follower tab on the camera body (the mechanical aperture coupler that transmitted the aperture value to the camera prior to the electrical contacts doing so). Many of those older Pre-Ai lenses have been modified by removing a portion of that skirt or thru replacement aperture rings that Nikon provided many years ago. if modified, the lenses can be used on any Nikon camera with an F mount.
dcampbell52 wrote:
On that camera, for any lens to be automatic, it HAS to have a silent wave motor (SWM) in the lens. The motor receives and sends signals to the camera body in order to focus. On the D7xxx and up versions, the body has a focusing motor built into the body to make it able to use the older lenses. Note, some of the older lenses have a tab for focusing and will not work on any of the bodies in the last 30 years or so.