is different think ~that 2 different type of camera ~cannot compare together ~Sony A7 is interchangeable lens camera / Nikon Df is DSLR Cmos same with Nikon D4 ~That why the price is more expensive~
compare the ISO only than u can see the different ~
Sony A7 ISO 25,600
Nikon Df ISO 204,800
The Nikon Df COMOS is same with D4 is very powerful ~ so the price higher than D800~ ...