New to Nikon cameras for video and feel like a newbie. Testing out a d800 with a set of Zeiss zf.2 lenses for video work.

When I put the camera in "M" manual mode all four zf.2 lenses we have still auto expose. For example, I can stop down and point the camera at a dark floor and the aperture ring will start to automatically rotate to a decent exposure without touching a thing. If I lock the exposure ring on the lens and try to use the forward camera dial for exposure nothing.

In the manual it says for CPU lenses in manual mode use the back dial for shutter, which works (24fps movie setting/50 shutter speed) and use the forward dial for exposure, not working.

Obviously not understanding something. I know it's got to be a menu or dial setting I just have not discovered yet. zf.2's do have a CPU for everything but AF so not sure what is going on. Any ideas?

Thanks!