Nikon has a new patent (2018-60041) for a zoom eyepiece for EVF. The full title is “Eyepiece Optical system, optical instrument and manufacturing method of eyepiece optical system“. Here is one set of specifications described in the patent:
- Focal length: 19.632 – 28.835 mm
- Object height: 6.350 – 6.350 mm
- Total length: 42.823 – 42.823 mm