If photography is authentically art, then photography in the context of art would need redefinition, such as determining what component of a photograph makes it beautiful to the viewer. Digital photography was used in astronomy long before its use by the general public and had almost completely displaced photographic plates by the early 1980s. Fine art photography includes photographs made to fulfill a vision, and reproduced to be sold directly to the customer. Landscape photography are photographs of different locations often made to be sold to tourists as prints or postcards. Modern digital cameras have comparable noise/grain at the same ISO as film cameras. Photography is used to preserve memories of favorite times, to capture special moments, to tell stories, to send messages, and as a source of entertainment. Photography as a usable process goes back to the 1820s with the development of chemical photography. Photography is a unique and creative medium of self-expression. When learning to be a professional photographer you should try entering photography contests. Many photographers agree that the commercially produced cameras were the single biggest drive to popularize the art form. Portrait and wedding photography is typically photographs that are made and sold directly to the families of the people in the images. Throughout the history of photography, technological advances in optics, camera production, developing, and imaging have had an effect on the way people view images. It is important to note that the differences between film and digital photography are far less significant than the differences between painting and film photography.