This paper introduces a hand-held plenoptic camera that samples the 4D light field on its sensor in a single exposure. By inserting a microlens array between the sensor and the main lens, the camera measures not only the total amount of light but also the direction of each ray. This allows for the computation of sharp photographs focused at different depths, achieving a linear increase in sharpness with the resolution of images under each microlens. The camera operates like a conventional handheld camera, but internally uses a microlens array to capture directional lighting information. The authors detail the optical design, theoretical performance limits, and experimental results, demonstrating the camera's ability to refocus and manipulate viewpoints. They also discuss the potential applications in photography, microscopy, and interactive photo albums. The paper concludes by highlighting the expanded design space for cameras and sensors, emphasizing the benefits of small pixels and the unique capabilities of light field photography.This paper introduces a hand-held plenoptic camera that samples the 4D light field on its sensor in a single exposure. By inserting a microlens array between the sensor and the main lens, the camera measures not only the total amount of light but also the direction of each ray. This allows for the computation of sharp photographs focused at different depths, achieving a linear increase in sharpness with the resolution of images under each microlens. The camera operates like a conventional handheld camera, but internally uses a microlens array to capture directional lighting information. The authors detail the optical design, theoretical performance limits, and experimental results, demonstrating the camera's ability to refocus and manipulate viewpoints. They also discuss the potential applications in photography, microscopy, and interactive photo albums. The paper concludes by highlighting the expanded design space for cameras and sensors, emphasizing the benefits of small pixels and the unique capabilities of light field photography.