I bought the Z6 along with the FTZ adaptor , with the understanding that I could use my F mount lenses. No problem with my Nikon 50mm or my Nikon 18-105mm, but my Sigma 70-300 will only focus manually. No autofocus!! Perhaps because it's not Nikon? This lens worked on my previous cameras; a D50, D90 and my D7100, so I naturally presumed it would work on the Z6!