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The Petzval Portrait Lens 1841

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When Daguerre marketed the Giroux camera it was fitted with the only lens reasonably suited for photography. Charles Chevalier a French lens maker had improved on a design by W.H. Wollaston in England about three decades earlier. Chevalier had followed his father, Vincent in the family business of telescopes and microscopes. He improved on Wollastan's lens by managing to limit the effects of two optical problems, chromatic and spherical aberration. This became known as a French Landscape Lens and was manufactured for many years under a variety of names.

Although it made a good image it had a serious flaw when used with the Daguerreotype Process. The speed of the Chevalier lens was f/16. The original Daguerreotype process was so slow that exposures could last as long as 30 minutes. Clearly, portraiture was impossible. People immediately wanted to make portraits. To make this happen a much faster lens was needed. To get the process underway a competition was announced with the winner receiving a gold medal. Of course, a fast lens would be patented and make a considerable profit for its inventor.

Joseph Max Petzval was a citizen of the Austro-Hungarian Empire. He had been born in 1807 in a village in what is now the Slovak Republic. At the time it was part of theKingdom of Hungary. A brilliant student he became a mathematician and physicist. Still a very young man he accepted the offer to design a faster lens and went to work. At this point in time the science of optical design did not exist. Certainly lenses had been made for many years before photography was invented and many of the problems of optical design were beginning to be understood. Most successful optical designs at the time were the result of trial and error. Petzval took a completely different approach. He designed his lens on paper first, using high order mathematical principals. When he had worked out the computations needed, he realized that it could easily take him a number of years to complete the calculations required to design the lens. There were no computers at that time. He then broke the design process down into a very large number of small sections. Then with the help of the Austrian Archduke who had command of the army, he was able to borrow about 12 of the military bombardiers since the country was at peace. These were the people who computed the gun elevation sand trajectories. They were familiar with logarithms and how to use log tables. Working under Petzval's direction they were able to complete the design of Petzval's lens in less than 6 months. This can correctly be thought of as a form of parallel processing, a term we now use with computers. Petzval's lens was mounted on the Voigtlander Daguerreotype Camera in 1841. The first version of his lens had a speed of F3.7 and was at least 22 times faster than the French Landscape lens then in use. With this len and a speeded up Daguerreotype process, a portrait could be made in less than a minute. This was the real beginning of commercial photography on a massive scale. Joseph Max Petzval was the first scientific lens designer.

Technical Details

Petzval Achromatic Portrait Lens

At first f/3.7 later improved to f/3.5

Focal Length [original] 150mm, but over at least 60 years

made in a large number of sizes.

For Further Reading

A History of the Photographic Lens

Dr. Rudolf Kingslake

Academic Press Inc. 1989

Last Updated ( Monday, 19 March 2012 20:38 )  

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