The Technical Notes series of Nature Documentaries aims to compile useful technical, theoretical and practical knowledge for documentary filmmakers. In this lecture from the FilmmakerIQ you will be exposed to some basic properties of the camera lenses such as the focal length and the aperture. The episode is also a good segway into sensor technology which also gets covered in more detail in another episode.
The episode gives a quick primer on focal length, field of view, diffraction theory and F-stops which are tightly related to sensor size. It also educates us about what is a 35mm “full frame” camera and crop factor. The episode delves into slightly esoteric technical subjects such as the relative concept of normal lens.
If you want to cultivate yourself further with optical theory you can check out the Khan Academy lecture series on Geometric Optics.