Hi Tim:
I edited this response for clarification:
On the camera, set the metering pattern switch to [: :], and not [:-:] or [ - ]. (Edit: On the AFD3 body a manual lens defaults to spot metering -- [ - ] -- regardless of how the metering pattern is set, so this only works with AFD2 bodies.)
Stop down manual metering or Av metering will work reliably on the AFD2 or AFD3 bodies to about f8 then it starts to get "iffy". The workaround is to meter more open, then manually adjust to equivalent EV for smaller apertures. (I use manual lenses in manual exposure mode for this reason, except the lenses I use for their wide-open look like the 80/1.9 or 110/2, which I normally use only near their maximum aperture anyway, so Av works great.)
An AFD3 body tip: Note that when in M or manual exposure mode on the AFD3 body, if you hold the AEL button down for more than a second, the shutter speed will automatically adjust to the correct level for the set aperture(!) Edit: This works with AF, MF or 3rd party lenses.
The lever on the side of the lens is the original stop down lever, I leave mine in the stop down position so that the lens changes aperture as I adjust it on the lens. There is mechanical linkage in that lens that was actuated in the manual bodies for auto stop down, but that actuator linkage is not present in the AF bodies.
Hope this helps!