Sony uses an lossy-compressed 11+7 bit file format in all their A7 series cameras as well as most others. Meaning bits are thrown away to keep the file size down. Most of the time, it works very well.
In theory “should not be visible” is the operative principle in this Sony lossy format.
If this is so, surely all medium format camera vendors and Nikon and Canon could all save us a huge amount of wasted storage space by lopping off all those unecessary bits, e.g. 8 bits is plenty, so why this 12-bit / 14-bit / 16-bit wastage? But all my experience with Nikon and Sony and other brands tells me that “should not be visible” is a crock—fine enough most of the time, but brittle.
This new page shows what a Sony histogram and a Nikon D810 histogram look like, using RawDigger to show the gapping of both. It proves nothing, but is provocative enough in the glaring differences.
Click for larger image. This is a crop of the full histogram.