Like the other second generation A7 cameras, the A7S II has internal 5-axis image stabilisation. For those unfamiliar, the pitch and yaw are corrected using stabilised lenses, but the second generation cameras also correct the X, Y and roll axis, which can be the most important for video.
For photographers they may notice that they can push the shutter speed slightly slower, around 0.5-1EV slower than previously. For videographers there is a much more noticeable difference when you are standing still and holding a frame. In our test we found that it is having the roll axis stabilised that makes the most difference. As you can see in our sample footage, the lens based stabilisation of the A7S and 24-70mm f/4 lens does a good job, but the addition of the X and Y stabilisation makes movements even softer and much more slight. However, it is the roll movements that become the most noticeable and that really give the A7S II the edge.
When moving with the camera the results of the stabilisation are less noticeable. Walking at a normal pace shows that there is little difference between the two cameras. The jolting movements of walking are too much to correct, thought again, the X, Y correction of the A7S II makes them fractionally less pronounced.
Walking at a more slower speed, with more considered movements, and the extra stabilisation of the A7S II is more noticeable producing smoother footage, though I would never rely just on the in-built stabilisation without any additional support for moving shots.
One of the key advantages to having the in-camera x,y, and roll stabilisation is that it means that any lens that is mounted can be stabilised. As I said earlier, we used a vintage Nikkor 50mm f/1.4 lens on the camera, and a quick delve in the stabilisation menu allowed us to input the focal length of the lens so that the camera new the level of stabilisation to apply, and the difference is noticeable. As videographers like to to put all manner of weird and wonderful lenses on their cameras this ability to stabilise third-party lenses is a very handy addition indeed.