Thanks Wade for confirming my first thought.
Edit: it looks as if the technology described in the patent provides a sort of focus peaking in the optical viewfinder. Cool.
The technology in the patent highlights sharp areas and helps to see how much depth of field you have (for instance at larger apertures).
- Patent Publication No. 2014-191184
- Published Date 2014.10.6
- Filing date 2013.3.27
- Canon patents
- Spreading factor variable finder screen
- First diffusion rate
- Brightness priority
- Setting of low diffusivity and high transmittance
- Second diffusion rate
- Blur priority
- Setting of high diffusivity and low transmittance
- The partially changed spreading factor according to the focusing range