RADOJUVA

Review of the Petzval 180 mm f / 4.5 lens (A. Darlot, Paris, 1862) specially for Radozhiva prepared Rodion Eshmakov (instagram).

At the dawn of photography - in the middle of the XNUMXth century - daguerreotype became widespread. The imperfection of photosensitive materials and optics forced the use of unacceptable for "live" photography excerptswhich was a big problem. And if the task of increasing the photosensitivity of silver halides was a headache for chemists for another century, then photo optics in the shortest possible time made a colossal step forward, largely thanks to one person. His name was Joseph Petzval - the father of the modern lens, mathematician and optician. Using a “neural supercomputer” with 10 computational units, he developed a lens with record parameters for that time: aperture reached F / 3.5 (about 10-20 times lighter than typical lenses of the era), the field used was 30 °. The optical design of the Petzval lens quickly became popular and was repeated many times by manufacturers of photographic lenses and telescopes-astrographs. The circuit has now been revived in optics manufactured by Lensbaby and the Lomographic Society.

The review presents an 1862 lens made by the famous French optician and entrepreneur Alphonse Darlot. This 180 / 4.5 petzval was apparently intended for the so-called. "Magic lantern" - the predecessor of the modern overhead projector.

Specifications:

Optical design - 4 lenses in 3 groups, "petzval";

Light diameter of the first lens - 40 mm;
Focal length - 180 mm;
Aperture ratio - 1: 4,5;
Aperture mechanism - none (projection lens);
Focusing mechanism - rack;
Enlightenment is absent.

Historical background

Includes partial translation of articles and notes: 1, 2, 3... Images taken here.

Origin

The process of daguerreotyping was first mentioned in passing in a brief note dated January 2, 1839, in the newspaper Le Drapeau Tricolore of Chalon-sur-Saone. A more detailed article was published in the Parisian La Gazette de France on January 6, 1839. It contained excerpts from a press release written by François Arago, who decided to support the new method of obtaining photographs by a famous physicist, astronomer and secretary of the French Academy of Sciences.

Arago persuaded the French government to provide Daguerre and Isidore Niepce (the son of Joseph Nicephore Niepce, who received the world's first photograph) with a pension in exchange for making the daguerreotype process publicly available and free of patents worldwide, except in England, where a patent was established (No. 8.194 dated August 14, 1839). Having ensured the financial well-being of the inventors, Arago, in the presence of Daguerre and Niepce, publicly presented the stages of the new photo process at a meeting of the Academy of Sciences, where members of the Academy of Fine Arts were also invited. It was the free distribution of the process that made it so popular, especially in Europe and the USA - photography went into the world. Edgar Allan Poe wrote in January 1840: "The instrument itself [daguerreotype] is undoubtedly to be regarded as the most important and perhaps the most outstanding triumph of modern science."

Although Daguerre received a pension from the government, he also entered into a lucrative deal with Alphonse Giroud, who began to manufacture Daguerre's equipment for creating daguerreotypes, including a camera, which became the first mass-produced camera.

Charles Chevalier created the first series of lenses for the Giroud camera. He was a well-known and very successful Parisian optician at the time, who manufactured the lenses of microscopes, binoculars and telescopes. It was Chevalier who brought together Joseph Nicephore Niepce and Daguerre, who were his firm's clients.

The Chevalier lens was a glued achromatic doublet with corrected spherical and chromatic aberrations, which was a modified telescope lens.

Achromat Chevalier had a pre-lens diaphragm that improves field aberration correction, and was oriented with a negative lens to the subject. Aperture was extremely low - F / 14, although to obtain a sharp image field, it was often necessary to additionally aperture the lens. Therefore, Giroud's camera required very long exposures (about 3-30 minutes) and was most suitable for still lifes and landscapes. Because of this, the achromat of Chevalier was called the "French landscape lens".

In the spring of 1840, the French Society for the Promotion of National Industries announced a competition (hereinafter referred to as the Society), "aimed at encouraging useful improvements in the art of photography." The deadline was set at the end of 1840.

Chevalier immediately set about designing a lens for the competition. After a series of experiments, he proposed a design consisting of two achromatic doublets located at a considerable distance from each other. He originally used a constant aperture at the front of the lens and achieved an aperture of f / 10, which was slightly better than his landscape lens, but still not enough. He then removed the diaphragm and further increased the distance between the doublets. The front component could now be oriented in different directions, while also changing the lens distance - thus Chevalier received a combined (and varifocal) lens with aperture of the order of F / 5. Chevalier presented it on December 1, 1840. Although the development was new, in the short "portrait" configuration the lens suffered greatly from optical distortion.

At the end of the competition deadline, in March 1841, the Vienna optical company Voitländer & Son presented to the Society a portrait lens designed by Josef Petzval (1807-1891), a Hungarian native and professor of mathematics at the University of Vienna. At the request of friend and colleague Andreas Ritter von Ettingshausen, Petzval focused his efforts on developing a lens that could be used for portrait photography. Since the calculation of the lens assumes the presence of time-consuming and complex calculations, Petzval used the help of ten gunners of the Austrian army (the gunners studied higher mathematics in preparation). So Joseph Petzval was able to calculate a lens that is capable of projecting a sufficiently flat field at a high aperture, after which Voitländer transmitted data on the refractive indices and dispersion of glasses to him and later made a prototype of the lens. Anton Georg Martyr, another professor at the University of Vienna with an interest in daguerreotype, participated in testing the lens and helped Voitländer prepare it for commercial sale.

The reason for such a late presentation of the Petzval lens to the Society was unknown - the Voitländer company began sales in November 1840 and on January 1, even released the first all-metal camera (Ganzmetallkamera) with a new lens.

For more than a year, the Society discussed the merits of Petzval and Chevalier lenses and, finally, on March 23, 1842, the competition was completed. Chevalier received the first prize - a platinum medal, and Voitlander - the second prize. Apparently, the national pride of French society leaped into the determination of the winner. The result was also influenced by the authority of Chevalier. Referring to the insufficient frame coverage of Petzval lenses, the Society gave priority to the empirically developed Chevalier product. In the end, history and the market have shown that the decision was wrong.

Petzval's design provided excellent correction of spherical aberrations and coma at a high aperture of f / 3.6, which was more than 2 times lighter than Chevalier lenses. The Petzval lens was the first mathematically calculated lens (Chevalier used trial and error). Petzval's calculations gave birth to the modern theoretical apparatus in optics and were subsequently developed by Seidel. Several terms in optics were named in honor of Joseph Petzval ("Petzval surface", "Petzval condition").

The main drawback of the new lens was the uncorrected curvature of the image field, which limited the field of view to 24°-30° (which corresponds to EGF ~85 mm). However, in portrait photography with a central composition of the frame, this was a minor drawback. The lens was just perfect for portraiture and marked the beginning of commercial photography, allowing the creation of daguerreotypes at a relatively low cost.

Optics design

In modern terms, the Petzval lens design consists of two thin achromats located at a great distance from each other. The front element is similar to a conventional achromat telescope objective. The rear element is a split achromat of two elements with very different radii of curvature - it corrects coma and spherical aberration of the lens. In this case, the rest of the distortions are uncorrected (especially the field curvature), which causes a strong drop in the resolution over the field of the frame and limits the angle of the field of view.

Due to its outstanding optical performance and lack of global patent protection (the patent was obtained only in Austria), the Petzval lens design was quickly copied around the world. Although many lenses produced by Voitlander are associated with the Petzval name, the name “Petzval” today refers to the design of the portrait lens indicated above.

Long-focus and high-aperture Petzval lenses turned out to be especially useful in projection installations ("magic lantern"), and their (and modified versions) use continued until the second half of the 4th century (in the USSR these were lenses of the P-5, P-6, P- XNUMXM, KO; in Germany - Kipronar, Kiptar).

Petzval Lens Manufacturers

High-quality Voitländer Petzval lenses have become the standard against which other portrait optics have been evaluated. In an 1851 article on the selection and comparison of photographic equipment, photographer and writer J. H. Fitzgibbon wrote: “Voightlander & Sohn from Vienna achieved the greatest notoriety in the world of daguerreotype for the excellence of their instruments, and they deserve their fame as their lenses are the best. of the currently known ".

High-quality Voitländer optics were highly valued in the market: their cost turned out to be twice as high as that of competitors. Despite initially dominating the market, competition quickly led to its division, especially in France: even Chevalier, who did not want to acknowledge the superiority of Petzval lenses and considered them a plagiarism of his design, went into their production from the 1850s.

The Petzval lenses, produced in the USA by the American Charles Harrison and awarded medals at the World Exhibition in London, also shattered the primacy of Voitlander optics. In England, Ross & Co. Her employee John Henry Dallmeyer founded his own company in 1859 and produced high-quality Petzval lenses. Dallmeyer is best known for designing the famous Rapid Rectilinear lens - similar to and independently developed by Aplanat Steinhel - that equipped cameras up to the invention of the anastigmata.

Other well-known manufacturers of Petzval lenses include: Emil Busch, Steinhel and Krantz from Germany; Vebl and Dietzler are from Austria; Zhamin, Darlo, Derogi, Ermagi - from France; Horn & Thornthwaite and Ray from England; Grubb from Ireland; Suter from Switzerland; Chapman & Lewis, Holmes, Booth & Haydns from USA.

Lenses of Jamin and Darlo

Jean Theodore Jamin in 1855 patented small modifications of the Petzval lens. First, he added a large cone-shaped element to the rear component, which is essentially a light deflector (lens diaphragm), which reduces the number of stray light reflections and improves image contrast. Second, the lens is made in such a way that the front element can be removed, inverted and used in place of the rear lens group, which transforms the lens from portrait to landscape. Thirdly, the lens made it possible to change the distance between the front and rear lens groups, which made it possible to eliminate aberrations at any distance from the object. It can be said that the concept of Petzval optics and Chevalier mechanics are combined in the Cone Centralisateaur lens by Jamin. Jamin and his partner and successor, Alphonse Darlot, have been selling these and other lenses (they also developed Hemispherique and Rectillinear lenses) for at least a decade, and they were especially popular in England and the USA.

Darlo from the age of 12 studied optics together with Lerebourg, later - in the laboratory of Jamin. From 1860 he collaborated with Jamin - until 1862 their names were jointly indicated on the bodies of their lenses. After the departure of Jamin in 1860, the management of the company passed to Darlo and the name of Jamin after 1864 was no longer indicated on the lenses. A rather successful entrepreneur, Alphonse Darlot sold lenses, projectors and photography kits that he developed. Contemporaries highly appreciated the merits of Darlo: in 1867 he received a silver medal at the International Exhibition in Paris, and in 1892 he was awarded the Order of the Legion of Honor.

Alphonse Darlot's company is the manufacturer of the lens featured in this article.

Design features

Almost all lenses of the mid-XNUMXth century have the same layout and represent a lens unit moving in the simplest frame with the help of a ratchet - a drive from a rack and pinion with a flywheel. In this case, the diaphragm mechanism can either be absent (mainly for projection lenses), or be in the form of a slot for installing Waterhouse insert diaphragms. Long known by that time, iris diaphragms became popular towards the end of the XNUMXth century, when the concept of depth of field was introduced.

Interestingly, all the body parts of the old lenses were made of brass. Chromed brass was also used in the 1930s, later replaced by lightweight and durable aluminum.

The 1862 Petzval Darlo, presented in this article, belongs to the group of projection lenses. It has a simplified design and does not have the ability to use aperture diaphragms. Unfortunately, the focusing mechanism of the lens has not been preserved.

This lens can be easily disassembled for cleaning without the use of special tools - a caliper or a special key is only useful for servicing the lens units themselves.

The inner surface of the lens unit housing was once covered with black velvet. However, the lens was in such a deplorable external condition that it had to be completely removed during cleaning and the surface was redrawn. The lens optics are surprisingly well preserved and show no major damage. The main problem was the presence of mold and clouding of the optical glue - the lens had to be glued and cleaned.
The lens optics are uncoated, almost 50 years were left before the invention of antireflection coatings. Over time, the glass of the front lens element has eroded and you can see rainbow film on it. It is worth noting that it was this phenomenon that prompted engineers and opticians to invent anti-reflective coatings: photographers noticed that old lenses with such glass do better in backlighting.

Like many old lenses, there is a significant amount of bubbles in the Darloh petzval lenses - this does not indicate any special quality, as some believe, but it does indicate certain problems in optical glass melting technology.

This lens was made from the most common types of glass. In those days, even barite glasses were not yet used. Therefore, this old petzval has a completely neutral light transmission, unlike its descendants from the XNUMXth century.

As you can imagine, there is no markings on the lens itself. How was the exact year of manufacture and manufacturer of this lens determined? Quite simply: each lens unit has a corresponding engraving on the lens ends. The hardest part was reading the handwritten text. But the parameters of the lens were determined empirically: the focal length - by comparing with the lenses I have, aperture - calculated according to the light diameter of the front lens and FR.

Since the lens is extremely old, it is not easy to fit into a modern camera. I didn’t want to irreversibly change the lens design and only attached a M62 threaded ring to its frame with glue in order to attach the resulting structure to the helicoid of the Soviet Volna-3B lens. Since the Darlo lens has a very large focal length, it turned out to be possible to use the usual adapter P6-M42. In front, I put on an impromptu hood on the lens. It would not be superfluous to make lens cut-off devices (as in Zamin-Darlo's shooting lenses :)), but I never got to their production. It is also good practice to paint over the ends of the lenses with black, but in this case it would be completely unacceptable.

Of course, a lens from the century before last can hardly claim a place in a photographer's wardrobe today. An attempt to apply it on a small format modern camera is more worth considering as a study. On the other hand, the illumined can apply similar optics on medium format cameras (the lens easily covers a 6 * 6 frame).

Optical properties

The Darlo 180 / 4.5 projection petzval has very good parameters for the 55th century and rather sad ones for the 200st: it can be classified as a "dark telephoto" - it is not much lighter than the class XNUMX-XNUMX zooms. Moreover, it is not a telephoto lens in terms of the optical design and is extremely large.

Nevertheless, the lens, which is 158 years old, has good image quality in the center of the frame: despite the generally low resolution, it cannot be said that everything is completely bad. The lens has spherical and chromatic aberration corrected quite well. I am even ready to assume that this lens in the center is not worse than the Soviet Telemar-22 200 / 5.6. As for the field, the resolution of the Darlot lens strongly decreases due to the aberrations of oblique beams and the curvature of the field, which is noticeable even at such FR and aperture ratio.

The biggest problem is image contrast. The optics are not enlightened, my copy also has a glued front component - there are as many as 8 glass-air surfaces (like the Planar!). Therefore, parasitic reflections bring a thick veil that cannot be removed. However, this should be largely corrected by a series of lens-cutters, since light reflections in the space between the matrix and the lens still make a significant contribution.

Below are sample photos taken with Sony A7s (shooting in RAW, processing in Imaging Edge).

Despite the fact that the image quality on the small format camera is quite poor, it feels like the lens can perform well in the medium format for which it was intended.

Conclusions

The Petzval lens performed by Alphonse Darlo is one of the first lenses that can be called modern: already calculated, already complex, no longer dark, no longer under 18 * 24. The fact that with the help of a lens a century and a half ago it is possible to obtain a generally watchable result (and with deep modernization while maintaining the optical part, I am convinced, the result can be good at all) is a clear demonstration that technology and technology are often secondary.

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