This lecture discusses the principles and applications of plenoptic cameras, also known as light field cameras. The instructor begins by explaining dual-pixel autofocus technology, which utilizes a micro lens above two sensitive pixels to determine focus by analyzing the difference in image positions. The lecture then introduces the concept of plenoptic cameras, highlighting their ability to capture four-dimensional light information through a micro lens array and photosensor setup. The instructor elaborates on the mechanics of light field photography, including the significance of the angle of incidence and the resolution of the sensor. Various applications of plenoptic cameras are presented, such as numerical refocusing, which allows for adjustments in focus after an image has been captured. The lecture also touches on the evolution of plenoptic cameras, referencing first and second-generation Lytro cameras and their specifications. Finally, the instructor draws parallels between plenoptic technology and other optical systems, such as sun sensors, emphasizing the underlying principles of light detection and spatial measurement.