The 6 is supposed to be better at low light due to their backlit sensor. Still, the Z5 is supposed to be better than the crop sensors. I was a little disappointed that my new Z5 wasn't head an shoulders better in resolution than the entry level crop sensor it replaced. I'm not disappointed in the camera overall, I was just hoping to see a bigger jump in rez. I would have loved to have gotten a Z7, but just too much $$$.