Rollei is one of those companies that, even though it was never the biggest (dwarfed by Kodak and Zeiss), the oldest (Voigtlander) or arguably the best (Leitz and Hassleblad), it developed a vast following of devoted users who loved their cameras.

The creation legend goes somewhere along these lines: Reinhold Heidecke was a camera-maker by trade. During World War I he was looking over the top of his trench with a periscope (or observing someone else doing so) and thought of an idea for a camera that used a similar principle: the camera would have two separate but identical lenses—a taking lens and a viewing lens. The photographer would look downward through a mirror through the viewing lens and see very close to what the camera saw. The idea would later become known as the Twin-Lens Reflex (TLR).

When the war ended, the legend goes, Heidecke returned to his job at Voigtländer and proposed his idea for the TLR, and was turned down—Voigtländer had more than enough cameras to build already. Heidecke left, formed his own company, and the rest is history.

Whether that's true is debatable. Historians point out that other people had made versions of TLRs before him, and when Heidecke did form his own company with partner Paul Franke in 1921, they didn't make TLRs, they made stereo cameras. I tend to believe Herr Heidecke developed his idea for the TLR from stereo cameras, which used two identical lenses to take two identical photos, except offset a few inches. Why not stand a stereo-camera on its end, wind the film across one lens, put a mirror on the other and use it as a viewfinder? The photographer would get a big, bright image that was nearly identical to the film image. Unlike a Single Lens Reflex (SLR), which required a mirror to have a hinge to flip out of the way, the TLR's mirror could stay fixed, allowing the photographer to see his image uninterrupted as the shutter fired.

The partners called their company Franke & Heidecke, and that is the proper company's name for most of its history. Their first camera was called the Heidoscop, a stereo camera that used sheet film or plates. They followed that up with a roll-film version that they called the Rolleidoscop.

By 1927 they introduced their TLR concept. Cameras with mirrors where historically called reflex canmeras, so they called their camera the Rolleiflex. It was a hit.

Over the next decade they rapidly evolved their little camera into a powerhouse. The first camera, the "original" Rolleiflex, was fairly simple, but as they added features and upgraded its quality, the Rolleiflex quickly became a professional-level camera. Unlike most roll film cameras (the Rolleiflex series all take 120) which used a red window and numbers printed on the film's paper back so that the photographer could advance the film using a thumb-wheel, the Rolleiflex used a crank-lever and a counting mechanism—no crappy red window to fog the film, no meticulous lining-up of the number in the window, no tedious, time-consuming turning of a knob. Add a quality Compur shutter, high quality Zeiss or Schneider optics, and a host of other nice features, and you had a hell of a camera. By 1937, just 9 years after it was introduced, the camera was largely set. There would be a number of a improvements and additions, but that would be evolutionary. The Rolleiflex of 1937 would be more-or-less the Rolleiflex of 2007.

The Rolleiflex quickly became the company's bread and butter. They down-scaled the camera to use 127 film, and it became known as the Baby Rolleiflex, and would be produced from 1931 to 1968, but it never really caught on. They fared better with their Rolleicord, a more modest version of the Rolleiflex, which they hoped to capture the amateurs who couldn't afford their Rolleiflex. But the lucrative amateur market was tougher to crack and the competition was fierce. Most companies sold TLRs that were pale knock-offs, but were far, far less expensive.

Franke & Heidecke fared better among commercial photographers. While it wasn't as versatile, the Rolleiflex was lighter and easier to handle than the popular press cameras of the era. It used 120 film, a medium-sized roll film that was well-established on the market. It's square 2 ¼-inch format was popular among many photo-editors who found it easier to crop the photos as they saw fit. The camera took a wide variety of accessories, and Franke & Heidecke kept the camera updated to accept various important accessories, as electronic flash.

But the 1960s were tough for German camera makers. The Japanese had pretty much killed the American camera makers in the 50s, and with their advances in quality they were able to take on the Germans. Nikon and Canon carved out the 35mm market, Mamiya successfully challenged medium-format with its C220 and C330 TLRs, among others.

Franke & Heidecke tried to diversify, with varying success. They created a line of 35mm cameras, from the rangefinder Rollei 35 to the Rolleiflex SLR series. The 35mm cameras were built in Singapore to lower costs, but their cameras were still too expensive to compete.

They continued to make and sell their flagship Rolleiflex TLR, but expanded their commercial camera line to include other medium-format wonders like the SL66 and 6006 series, with varying success. While still highly regarded, the competition was simply too fierce. In 1981 Franke & Heidecke went bankrupt.

After that, the name went through similar indignities that befell rival Voigtländer as the company was bought and sold several times, though unlike Voigtländer it has managed to continue production. And unlike most camera makers with multiple corporate lives, has managed to retain its reputation a quality, professional-grade manufacturer. It is currently run by a Scandinavian investment group.