The Nikon D4s is pretty much an all-around faster Nikon D4 but one of the biggest hidden changes made to the camera was a new mirror dampening mechanic. The D4s manages to eke out one extra framer per second compared to its predecessor and now Nikon has put out a video showing exactly how they did it.
Using a Nikon 1 V2, Nikon Europe put together a 1200fps extremely slow motion video of the two cameras firing side by side. As you can see the mirror dampening helps stop the mirror from bouncing back while it’s firing away at 11fps. Hopefully stabilizing the mirror with dampening will help in the long run to reduce the wear and tear on the camera body’s interior components.