The modern era of photography began in 1861 with the invention and patenting of the world's first single- lens reflex (SLR) camera by photography expert Thomas Sutton (1819-1875). His prototype led to the creation of the first batch of SLR cameras in 1884, with a design that f5 still in use today. Sutton also assisted James Clerk Maxwell in his successful demonstration of color photography in 1861.
In non-SLR cameras, light enters the viewfinder at a slightly different angle to that at which it enters the lens, so the resulting photo can appear different to the intended composition. In SLR cameras, a mirror is positioned in front of the lens and directs light up into a pentaprism. The light bounces between its edges until it enters the viewfinder with correct orientation, as if the viewer is looking directly through the camera lens. When a photograph is taken, the mirror moves out of the way allowing light to reach the film or, with digital SLRs (DSLRs),the imaging sensor.
Now the most popular professional camera format, the SLR camera was the culmination of decades of photographic innovations that began with the production of Louis Daguerre's daguerrotype and Josef Maximilian Petzval's lens systems, which led to the first mass-produced cameras.
Although no record of the first production model exists, the camera was first commercially produced in the mid-1880s. By the 1930s it was extremely popular with photographers, allowing an undistorted view of the subject from the correct perspective. DSLRs have all but replaced the traditional SLR, but the principle that Sutton pioneered is still used today.
