Wait a second. Doesn't the 12-24 lens cover the full frame from 18mm up? My Tokina 12-24 does. If that's the case, it seems to me you would get the full benefit for at least part of the zoom range. I use my 12-24 on my N80 all the time from 17mm/18mm and up without any cropping. Or do DX lenses automatically put an FX sensor camera into DX mode?