Digital Single-Lens Reflex Cameras
The birth of photography for everyone
The principles of photography are pretty simple. Light enters a box through an aperture, hits a responsive plate or film which is then developed to reproduce the image. Pinhole cameras are the most basic example of the science, and for many years at the beginning, nothing much changed. The lenses were often short with poor focus and the responsive plate was unreliable and fragile. Gradually things improved, but the whole process was slow, complicated and impractical. We have all seen the old images of the 19th century photographer, his head tucked under a sheet while the subjects froze for minutes until the chemical had worked their magic. Whilst this system can produce some remarkably sharp and richly detailed images, they are not portable to any degree and today, tend to operate in professional studios.
Progress enabled improvement in both the film and the lenses, but the problem was that, with the film in the camera, the photographer could not see through the lens to focus and compose the image. Top view cameras were produced, which allowed you to look over the top of the lens, rather than through it, but the lenses could not be focussed. The SLR addressed this. In the 1930s the first mass produced SLR appeared from Leica. It contained a mirror, that enabled the photographer to look through the lens while the film sat behind, ready to be exposed when the shutter opened.
This launched photography as we know it today – portable, accessible and very popular.
Although film has given way to digital, the requirement to look through the lens to focus remains, and so the D-SLR ( digital single-lens reflex) is now the common multi-lens camera body.
Compact cameras have led the way in removing the need for a view finder by having live-view screens at the back of the camera. The purists might baulk at the idea, but the next step in photography will be the removal of the mirror in the SLR and another jump in evolution in shape and function will result.