Lenses and photographic processes
Early photographic processes were intertwined with inventions in the fields of camera-making and especially lens-making - a complete new field for innovations.
Early photographic processes were intertwined with inventions in the fields of camera-making and especially lens-making. While cameras were made by skilled carpenters, the manufacturing of lenses was a complete new field. As soon as new technologies in making glass advanced, new lens systems were developed especially for photographic applications.
Petzval’s calculations
As soon as camera-based processes like the Daguerrotype (1839) and Kalotype (1835) became more and more popular, photographers wanted to have better lenses that reduced exposure times and improved optical qualities. One lens maker, Chevalier, sold a camera & lens kit under license of Daguerre but the lens did not have the best qualities. Around 1839, times were changing rapidly after Daguerre’s invention. Especially in Vienna, a small group of men around Ettinghausen, Martin, Petzval & Voigtänder were impressed by the new process. Just a few months later, the Mathematician Josef Petzval started to design a new type of lens. This design process was different: while other lens makers made their lenses by trial and error, Petzval was the first optician who calculated the lens.
With the help of the Austrian army, he was supported by 8 men who were firm in calculations and months later, in May 1840, the calculations were complete. The new lens was a portrait lens with three lenses in two groups: the Petzval lens. The lens was incredible fast with an f-stop of 3.7 - it reduced exposure times from minutes to only seconds.
Just after Voigtländer made the first prototype with Petzval‘s new lens design, he sold a daguerrotype camera including the lens. A very successful business case - but the lens design was not patented and Petzval only got a small amount of money for his invention. Since Voigtländer and Petzval did not patent the lens design, many copies did emerge in the next years. Some had modifications, like Dallmeyer‘s Patent Portrait lens, but others did not have a good glass quality like Voigtländer lenses.
Nevertheless, the Petzval‘s lens offered short exposure times and good sharpness & contrast in the center of the projected image. It was dominant in portrait studios, in modern times, photographers are using the romantic „swirl“ of the image when using the lens wide open on a bigger film or plate.
Portraits, but what about landscape lenses?
Photographing landscapes did not require short exposure times like portraits, but small lens designs that produce a fairly bright image on the ground glass were in need. Also, a sharp and contrasty image should be projected on the plate.
The single achromat was a lens type that was widely used by many photographers. It consisted of two glass elements in one group and produced a bright image on the ground glass with f16. It was very sharp when stopped down two or three stops and very fast for UV sensitive processes like Daguerrotypes or wetplate collodion, because the light could pass all glass elements with not much loss in brightness. Some lens makers, especially Darlot in France, sold Petzval portrait lenses with the possibility to use the front element for landscapes. This made it easy for photographers to buy only one lens for multiple purposes.
The single achromat lens design had a very narrow field of view, so the demand for a wider view was given from the beginning. The most exceptional lens design was the globe design. It was a symmetrical lens - meaning the front and the back elements were identical and offered wide angle views. Some makers were Harrisson & Schnitzer (Globe lens, USA), Emil Busch (Pantoskop lens, Germany) or also French lens makers.
Since I am using the Pantoskop lens, I can give a short review about the lens. The lens itself is very light weight, having a slot for waterhouse stops and is quite slow with a f22. Focussing in dim light with f22 is quite difficult, but manageable with a good dark cloth. I still can not wrap my mind around how they could make those fragile, curved lens elements back in 1860, but they definitely were ahead of their times. Stopped down 1 or 2 stops, the lens offers a sharp image until the corners of the coverage while being extremly wide. My Pantoskop No. 4 lens was designed for 24x30cm plates with a focal length of 180mm (20mm equivalent to 35mm film).
The pantoskop lenses were corrected, so no spherical abberation was given. This is the reason why that lens was used for photogrammetry.
This is it for now, probably I will continue writing about lenses and especially about where you can find and buy them now. Until then, take care and thank you for sharing this.