How to carry out research study on photography?

There are many topics that can be done, such as exposure, tone, color, composition, focusing, perspective and so on.

Simple examples, such as "the relationship between depth of field and aperture", need to take some photos of various apertures with a manual camera, with appropriate theoretical analysis and elaboration.

Other reference topics: the relationship between lens focal length and depth of field, shutter speed and exposure, aperture and exposure, tone level.