Hans Schulz - The father of the VEF Minox lens?

Minostigmat lens of VEF Minox Riga. Photo by Burkhard Fenner The lens that really shouldn’t have worked Imagine you want to build the world’s smallest camera. A mechanical marvel, no bigger than a lighter. But there’s a problem: there isn’t a lens in the world sharp enough to capture an image on a piece of film the size of a fingernail. The industry giants were in agreement. When Walter Zapp approached Agfa in the 1930s to jointly develop the lens, they coolly turned him down. Too exotic, too risky, simply unfeasible. At Leitz in Wetzlar, the Olympus of optics, they didn’t even deem a response necessary – they simply ignored him. To the experts in Munich and Wetzlar, the Minox was not a stroke of genius, but an optical pipe dream. A “lemon,” even before the first sketch was finished. But while the market leaders were still explaining why the laws of physics were against Zapp, he found someone who wasn’t intimidated by the big names. In his lab, a brilliant expert set to work on a task that is almost forgotten today: he calculated the impossible. He ignored the arrogance of the established players and designed a lens so sophisticated and tiny that it didn’t appear in any textbook. It was the birth of the Minostigmat – a lens that wasn’t supposed to exist, but would change the world of photography. The Minostigmat:7 mm in length At this point, I would like to thank Ralph T. Schwarz, without whose crucial clue regarding the identity of Hans R. Schulz this article would not have been written. Furthermore, his research into Schulz’s biography contributed significantly to a complete picture. I would like to extend my special thanks to Heinz Humberg, who provided me with valuable insights into the optical and physical aspects of this topic. I would like to thank my friend Burkhard Fenner for the unique photos of the Minostigmat and its accurate dimensions. He also provided me with ongoing inspiration for this article and served as my discussion partner. Dace Kaprāne looked through the documents on the Minostigmat for me at the VEF History Museum. I would like to thank her very much for that.

I am grateful to Hubert E. Heckmann for sharing valuable insights from his conversations with Walter Zapp and his own reflections on this topic. I would also like to thank him for carefully reviewing the final draft and for his comments on it. Page ContentsThe lens that really shouldn’t have workedWho was the man behind the Minostigmat?The Minostigmat – Heart of the VEF Minox RigaChallenges for a lensHans Schulz – Father of the Minostigmat LensDesign and calculation of a Cooke tripletResult: The MinostigmatConclusionMinostigmat test photosMore information about the VEF Minox RigaReferences The Shadow Behind the Monument Walter Zapp is a name that stands like a monument. His 1935 design for the first Minox is considered the “Big Bang” of subminiature precision engineering—the birth of a camera that created its own legends. Yet every monument casts a shadow, and hidden within that shadow is the single component without which the Minox would have remained blind. Heckmann1 in his standard work Variations in 8×11 reminds us of the man behind the glass: “After a grueling wait, these [the optical data for the lens] were finally calculated by Prof. Schulz in Vienna.” VEF Minox Riga with Minostigmat This is all that posterity has left of the man who transformed Walter Zapp’s precision mechanics into a functioning tool. Zapp possessed the vision to build a camera that could disappear into a clenched fist—but he was no optician. He could design the mechanics, but he could not master a lens. Who was the man behind the Minostigmat? Anyone looking for the man who gave Minox its eyesight won’t find a Wikipedia entry. All you’ll find is a “Professor Schulz” from Vienna. “At the time, I had asked Walter Zapp several times about the lens calculator Prof. Schulz from Vienna. Zapp could only confirm this fact, but he didn’t even know the professor’s first name. Based on what I knew at the time, I suspected that Prof. Schulz worked at or for Voigtländer or C.P. Goertz. Unfortunately, Zapp was unable to confirm this.”

Hubert E. Heckmann tells me. Prof. Hans Schulz in the course catalog of the Technical University of Berlin 1934/35 To find the true architect of the Minostigmat, one must descend into the dusty catalogs2 of the Technical University of Berlin, 1934. There, buried among the lists of specialists in applied optics, a name emerges: Prof. Dr. phil. Hans Reinhold Theodor Schulz He lived in Berlin-Lichterfelde. He taught physiological optics and the polarization of light. He was the man who understood not just how glass bends light, but how the human eye—and the film—perceives perfection. Technical University of Berlin in the 1930s The industry giants at Agfa and Leitz had already turned Walter Zapp away, convinced his vision was a technical dead end. They saw a “lemon.” But while the “tenured” elite looked elsewhere, this “non-tenured associate professor” Schulz was navigating a different kind of pressure. There is no direct evidence available that Hans Schulz was indeed the optics specialist commissioned by Walter Zapp. I have found no unequivocal information on this in the Minox literature or online. The only circulating reference is the aforementioned hint to a “Professor Schulz” who supposedly received this commission in Vienna.

To understand if he was indeed the one who gave the Minox its sight, we must look at a revelation he published in 1940 – a blueprint for a lens that, according to the optical establishment, shouldn’t have existed at all 3. Light Through Glass – A Popular Introduction to the Problems of Optics But before we can look at Schulz’s private records, we must first understand the battlefield on which he fought. To appreciate why the giants of the industry deemed Zapp’s vision ‘impossible,’ one must understand the invisible enemies of any lens: the optical aberrations that haunt every piece of glass. In the following chapters, we will deconstruct the anatomy of a camera lens and the complex problems that Schulz had to conquer. Only then, equipped with this knowledge, can we return to the man himself—and examine the decisive evidence he left behind in 1940: a blueprint that finally reveals how he tamed the light.

The Minostigmat – Heart of the VEF Minox Riga In the world of subminiature cameras, the Minox is often regarded as the ultimate. Anyone who takes a look inside immediately realizes that the shutter is the most complex mechanical component in the entire camera. This mechanical masterpiece controls the exposure times with a precision more reminiscent of a Swiss watch than a camera. The truly critical component, however, is another. With a negative format of just 8 x 11 mm, the lens determines the camera’s usability. The Riga Minox lens, called Minostigmat, was therefore far more than just a component; it was the Minox’s raison d’être. Only its edge sharpness and light intensity transformed an ingenious mechanical design into a serious photographic instrument. Developing a lens is no easy task, even today. Back in 1935, the Minox lens design faced additional, nearly insurmountable challenges. So let’s start by considering what criteria an outstanding lens had to meet back then. The lens on the Riga Minox is called Minostigmat. The name consists of two parts: the first part identifies the lens as a (miniature) component for the Minox camera, while the second part refers to its construction as an anastigmat. Challenges for a lens If you’re familiar with the optical challenges of camera lenses, you can skip this chapter. But if you’d like a summary tailored to our topic – explaining why a camera needs a lens and what challenges arise in lens design – keep reading. Don’t worry, everything is explained in an easy-to-understand way. Why does a camera need a lens? A camera doesn’t necessarily need a lens. A pinhole camera uses the straight-line propagation of light to create an image. A tiny aperture controls the selection of light rays. This small hole allows only a very narrow beam of light to pass through from each point on an object. This beam strikes the opposite wall, where it creates a small image point. Photographed with a pinhole camera at an exposure time of 20 minutes But pinhole cameras have physical limitations. Since very little light passes through the small hole, extremely long exposure times are required.