Here we are comparing two cameras with different body types: Nikon D3S, which was introduced in February 2010 is a Pro DSLR camera with a 12.0MP Full frame sensor whereas Sony A9, which was introduced in April 2017 is a Pro Mirrorless camera with a 24.0MP Full frame sensor.
Despite some fundamental differences of these two body types, Mirrorless cameras are becoming serious alternatives to DSLR cameras thanks to their size/weight advantages and recent improvements in their focus speeds , which makes this comparison even more interesting. Fortunately, you can't go wrong with any of these cameras as we rank them amongst Top 10 cameras in their classes. Nikon D3S is ranked #7
out of 34 Pro DSLR cameras with an overall score of 68 whereas Sony A9 is ranked #8
out of 38 Pro Mirrorless cameras with an overall score of 94.
Let's have a brief look at the main features of Nikon D3S and Sony A9 before getting into our more detailed comparison.