A Brief History of the Convertible Lens System


We walk you through one of the most brilliant ideas to change photography and its conception by inventor and pioneer Charles Chevalier -- the Convertible Lens System.

What is a convertible lens?

The convertible lens, a lens which consists of two or more interchangeable and usable glass elements have been around since the late 19th century. This was usually used by amateur photographers to aid them in extending the folding camera for more versatility. There were a lot of variations of the convertible lens, the most popular consisted of a pair of lens tubes, with one to be screwed at the back of an aperture/shutter unit, the other one at the front, and they are mounted in such a way the combined elements would make up to the standard lens, using a single extension of the camera bellows.

But, how did such gear came to be? It all began with a passionate lensman, named Charles Chevalier.

Charles Chevalier: the genius behind the convertible lens system

The conception of the convertible lens system was made during a contest in the late 19th century, France. In the spring of 1840, the Société d'Encouragements pour l'Industrie Nationale (Society for the Encouragement of National Industry) announced a competition, " “wishing to encourage useful improvements in the art of photography". The prize for the best invention or improvement was in the form of cash and medals, in which the winners would be dubbed as the ones "who are bold enough to put to the test useful improvements to the art of photography". The contest deadline was at the end of the year.

The French lensman and optician Charles Chevalier began to develop a lens for the contest. He experimented with a lens that featured two achromatic and cemented doublets, parted away from each other with a fixed aperture at the front. The aperture was f/10, and was faster than the original f/14 landscape lens he made. This was his first submission to the contest.

Images sourced from Lomography France

His second submission was a further improvement of the lens -- increasing the distance between cemented doublets by adding the interchangeable component of the barrel and removing the stop altogether. The aperture increased to f/5.2, and the focal length was shortened to be fitting for portrait photographs. The interchanging and converting nature f lens from a landscape to a portrait configuration simply by replacing the barrel was that the birth of photography's first convertible lens, named "Photographe à Verres Combinés". It is also known as "L'Objectif Double ou à Verres Combinés", meaning the "double lens or combined glass".

Chevalier presented it to the Society on December 1, 1840, and won first prize with a platinum medal, against a major lensmaker rival, Voigtländer for the Petzval lens.

Legacy of Chevalier's convertible lens system

Chevalier's convertible art lens system launched more improvements. At the end of the 19th century, many lens makers sought out to explore Chevalier's system. There was Jean Theodor Jamin, who patented his Objectif Double à Cône Centralisateur (Double lens with Centralizing Cone) on March 7, 1855. Jamin adopted Chevalier's idea of a convertible lens and marrying it with Petzval's optical design.

Some makers also designed symmetrical lenses in which each half was meant to be used alone, such as the Zeiss Protar Series VII, the Ross Combinable and the Goerz Pantar. There was also Contaflex, which adopted the convertible lens system for their 35mm SLR cameras in the 1950's; there was Canon EXEE and EX Auto of the 1970's. Most modern convertible lenses often have three four or more elements, some with double-focus lens instead of single-focus or zoom lens.

In terms of photographic use, the most famed user of a camera with a convertible lens system is Ansel Adams. His photographs such as "Moonrise", "Clearing Winter Storm, "Aspens" and "Mount Williamson" were used with Cooke Series XV triple convertible lens. Many photographers -- then and now -- believe that older convertibles remain compatible when making negatives for contact printing.

Information are collectively sourced from Large Format Photography, Camera-wiki and Antique Cameras.

We’re back on Kickstarter with the Neptune Convertible Art Lens System — ensuring you have everything you need for any photographic opportunity. With three interchangeable front lenses with fixed focal lengths of 35mm, 50mm or 80mm, be prepared for any shooting situation with just one lens system. Including six special aperture plates that create beautiful and delicate bokeh, create stunning images with endless creative combinations. Inspired by Charles Chevalier’s original invention and reimagined with a smooth and sleek design, this multi-coated lens is an ideal option for beginners and professionals alike whether you shoot analogue or digital.

Back us on Kickstarter now to save up to 45 percent on a Neptune Convertible Art Lens System and a range of exclusive extras!



  1. tretti
    tretti ·

    “The shutter speed increased to f/5.2“
    Come on! 🙈 Do you even read the articles before you publish them?

  2. cielsan
    cielsan ·

    @tretti thank you for pointing it out! We have already corrected the mistake. :)

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