Originally posted by Penview52 " ..Are you sure? MF vs AF shouldn't matter.. "
Try it, MF is the way that the shutter will release even when the aperture is not in " A " settings, except when this lens is restricted on pentax camera.
It will release, except focus confirmation has to take place, as focus-priority AF-S is normally engaged, it will also apply to MF operation or to a MF lens.
The aperture ring use in menus is found in the "C" Custom menu #4, I believe. Select "permitted". You can just leave it that way when going back to a regular AF lens, so you don't have to go menus all over again.
Then shoot in M Manual mode on your mode dial, and use the green button to automatically close down aperture and meter as the camera sets shutter speed, after your having manually selected aperture via the aperture ring. There will be no display of aperture, except on the ring itself.
Keep in mind that now the camera is converted mainly to a ye olden manual/aperture priority camera, having centerweighted metering. Your matrix metering automatically switches to centerweighted. This will be displayed. Getting accurate exposure is a little tricky. Try pointing to a brighter area of the scene having some mid-tone color- like well-lit grass (but not too bright like the sky on a sunny day!) to get your metered exposure with the green button, then reposition your camera to get your shot.
If you ever get an old MF common variable-aperture zoom lens to be used in this manner, keep in mind that since you don't have electronic aperture control, only mechanical, as you zoom the aperture value will deviate from what you select on the ring, getting narrower as you zoom to a longer FL, so then you have to re-meter with the green button.