fStop above 22 is generally not needed for such a scene since 22 is also an extreme value. You should better try 8 or 11 and re-compansate the exposure with increasing shutter speed. I can see there're fields out of focus even with fstop value 50, then it should be about wrong scale.
Your definitely a rendering machine, but remember one super fine image is worth 20 or more average ones. Take your time tweaking textures and lighting, when you get it Maxwell perfect........then just let it burn til she's good and done.