There is no magic in bigger sensor, there is no magic in optics, just a very different marketing point.
The pictures have been taken with an HC 50-II. Can we find the equivalent lens for the D800 (or any other full frame camera)?
The HC 50-II:
-is 116mm long
-is open at f/3.5
-uses 11 elements in its optical design
-costs €3555 without VAT
An equivalent lens for the D800 does not exist, but we can imagine one: we will suppose that we have a reducing machine which can make everything smaller in all dimensions. We make everything 40% smaller, so that we get a 35mm lens. What would that lens be? It would:
-be 82mm long
-weight 355g (the weight is divided by the cube of the distance, so 1.4^3)
-still be open at f/3.5 (aperture is dimensionless)
-still use 11 elements
-still cost €3555 (actually, maybe a bit less if we could benefit from economies of scale, but not less than, say, €2000-2500, because it is still a very complex design).
And there lies the difference. Actual lenses for the 35mm format are very different. You do not have an 11 elements f/3.5 in 35mm format at any price. Nobody would buy them. You have:
-either very fast lenses, so they are optimized for very different criterias
-or slower lenses, but they use relatively simple optical designs with 5-6 elements so are poorly corrected.