

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