Canon Patent Applicaton: EVF Optical Design

In this patent application Canon does something completely different.  One of the issues surround EVF optics is of course size.  with any optical system you have the three main definers; size / weight, price, quality - one generally affects the other.  if you want a high quality optic, it usually is bigger and costs more.  if you want a smaller / lighter lens, atypically it's quality is less and so on.

Canon in this case, "folds" the light path to make the EVF system more compact and have a wide field of view.  Can you say full frame EVF anyone?

In Canon's own words;

In recent years, so-called mirrorless cameras that do not use an optical finder have been proposed for interchangeable lenses (imaging devices) and the like. In a finder used for a mirrorless camera, an EVF (electronic view finder) is used that enlarges and displays an original image displayed on an image display element such as an LCD via an observation optical system. Here, the observation optical system applied to the EVF is required to have high optical performance, be small in size, and have a wide observation angle in the observation visual field.

Just to explain a bit of the diagram;

In the lens sectional view, L0 is an observation optical system, SP is a diaphragm, (observation plane), and (pupil plane). ID is an image display surface. G1 is a first optical element (lens G1), and G2 is a second optical element (lens G2). G3 is a third optical element, G4 is a fourth optical element, and G5 is a fifth optical element. HM1 is a first semi-transmissive surface (semi-transmissive reflective surface), and HM2 is a second semi-transmissive surface (semi-transmissive reflective surface). E is a polarizing plate. The "optical element" in the present specification includes a lens having a refracting power and a parallel plate glass having no refracting power.

Japan Patent Application 2020-095073