This paper presents a hand-held plenoptic camera that samples the 4D light field on its sensor in a single photographic exposure. The camera uses a microlens array between the sensor and main lens to capture light rays from different directions, enabling refocusing and synthetic photography. By re-sorting the measured rays, the camera can compute sharp photographs focused at different depths. The resolution of images under each microlens directly affects the sharpness of refocused photographs, allowing for extended depth of field without reducing the aperture. This enables shorter exposures and lower image noise, especially in macrophotography. The camera operates like a conventional hand-held camera, with the same viewfinder, focusing mechanism, and exposure settings. The paper describes the optical design, including the placement of the microlens array and the matching of main lens and microlens f-numbers to maximize directional resolution. It also discusses the theoretical performance limits of refocusing and the ability to reduce noise by refocusing. The camera's capabilities are demonstrated through examples of portraits, high-speed action, and macro close-ups. The paper also addresses issues such as vignetting and provides techniques to alleviate it. The implementation uses a medium format digital camera and microlens array, with results showing the camera's ability to produce sharp images with extended depth of field. The paper concludes with examples of light field photography, including refocusing and viewpoint manipulation, and discusses potential applications in photography, movies, and scientific imaging.This paper presents a hand-held plenoptic camera that samples the 4D light field on its sensor in a single photographic exposure. The camera uses a microlens array between the sensor and main lens to capture light rays from different directions, enabling refocusing and synthetic photography. By re-sorting the measured rays, the camera can compute sharp photographs focused at different depths. The resolution of images under each microlens directly affects the sharpness of refocused photographs, allowing for extended depth of field without reducing the aperture. This enables shorter exposures and lower image noise, especially in macrophotography. The camera operates like a conventional hand-held camera, with the same viewfinder, focusing mechanism, and exposure settings. The paper describes the optical design, including the placement of the microlens array and the matching of main lens and microlens f-numbers to maximize directional resolution. It also discusses the theoretical performance limits of refocusing and the ability to reduce noise by refocusing. The camera's capabilities are demonstrated through examples of portraits, high-speed action, and macro close-ups. The paper also addresses issues such as vignetting and provides techniques to alleviate it. The implementation uses a medium format digital camera and microlens array, with results showing the camera's ability to produce sharp images with extended depth of field. The paper concludes with examples of light field photography, including refocusing and viewpoint manipulation, and discusses potential applications in photography, movies, and scientific imaging.