History of the Dingle-Lens Reflex Camera

The history of the single-lens reflex camera predates the invention of photography in 1826/27 by one and a half centuries with the use of a reflex mirror in a camera obscura first described in 1676. Such SLR devices were popular as drawing aids throughout the 18th century, because an artist could trace over the ground glass image to produce a true-life realistic picture.

A British patent was granted in 1861 for the first internal mirror SLR photographic camera, but the first production photographic SLR did not appear until 1884 in the U.S.

Cross-section view of a typical 35mm SLR camera:
1 – Front-mount Lens
2 – Reflex mirror
3 – Focal plane shutter
4 – 35mm film or sensor
5 – Focusing screen
6 – Condensing lens
7 – Pentaprism
8 – Eyepiece

These primitive SLR cameras began to mature in the early 20th century, but their many disadvantages continued to make them unsatisfactory for general photographic use for decades. The SLR may be elegantly simple in concept, but it turned out to be fiendishly complex in practice. The SLR's shortcomings were solved one by one as optical and mechanical technology advanced and in the 1960s the SLR camera became the preferred design for many high-end camera formats.

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In the 1970s, the addition of electronics established an important place in the mass market for the SLR. The SLR remains the camera design of choice for most professional and ambitious amateur photographers.

Early large and medium format SLRs

The photographic single-lens reflex camera (SLR) was invented in 1861 by Thomas Sutton, a photography author and camera inventor who ran a photography related company together with Louis Désiré Blanquart-Evrard on Jersey. Only a few of his SLR's were made.The first production SLR with a brand name was Calvin Rae Smith's Monocular Duplex (USA, 1884). Other early SLR cameras were constructed for example by Louis van Neck (Belgium, 1889), Thomas Rudolphus Dallmeyer (England, 1894) and Max Steckelmann (Germany, 1896), and Graflex of the United States and Konishi in Japan produced SLR cameras as early as 1898 and 1907 respectively. These first SLRs were large format cameras.^[2][3] While SLR cameras were not very popular at the time, they proved useful for some work. These cameras were used at waist level; the ground glass screen was viewed directly, using a large hood to keep out extraneous light. In most cases, the mirror had to be raised manually as a separate operation before the shutter could be operated.

Following camera technology in general, SLR cameras became available in smaller and smaller sizes; medium format SLRs soon became common; at first larger box cameras, and later "pocketable" models such as the Ihagee Vest-Pocket Exakta of 1933.