Solar camera

The Solar Camera is an ancestor of the darkroom enlarger, and was used in the mid 19th century to make photographic enlargements from negatives.

Description

Early photographic materials were less sensitive, and exposures required in making copies from negatives increase inversely with enlargement. Photographers therefore employed the most powerful light source then available; the Sun. Solar cameras were at first freestanding, a design based on picture-taking cameras but with the relative position of negative and lens reversed so that sunlight shone through the glass plate to be projected onto photo-sensitive paper or an emulsion on other substrates (glass, fabric, leather etc.) inside the instrument. Mounted on a stand, they could be rotated to continuously face the Sun.

Inventors

A number of photographers, inventors and photographic businesses contributed to the design development of the solar camera. A predecessor was the solar microscope, employed by Thomas Wedgwood and Humphry Davy in making the first, but impermanent, photographic enlargements.

Woodward's 1857 solar enlarging camera was a large instrument operated out-of-doors that could produce life size prints from quarter plate and half plate negatives with an exposure of about forty-five minutes. In the 1860s and 1870s improvements included a clockwork heliostat, such as that invented by Léon Foucault in 1862 and built by his son-in-law, to rotate the mirror in synchronisation with the Sun's passage to concentrate its light on the condenser lens.

Jacob Wothly of Aachen improved Woodward's design with a reflector and presented it to the Societe Francaise de Photographie in early November 1860, selling the design to Disderi, reportedly for 20,000 francs soon after, who was awarded a medal for his enlarged photographs at the 1862 London International Exhibition.

M. Monckhoven's 1864 solar enlarger (engraving)

Désiré van Monckhoven's Belgian August 1863 patent for “an optical apparatus intended for enlarging by projection” was a modification of Woodward's design and had an appearance more like a modern horizontal enlarger. It corrected for spherical aberration (“appareil solar dialytique”) for sharper, more even light, for which he received a bronze medal at the Exposition Universelle (1867). After securing patents in England and France he went into manufacture. His apparatus was built into the darkroom wall, while J.F. Campbell’s vertical design of the following year gathered light through an opening in the roof.

Nadar used Alphonse Liebert’s enlarger for his first enlargements around that time, a design which used a hand-operated drive to keep the condenser lens focussed on the sun directly; with no mirrors, exposure times were decreased.

Louis Jules Duboscq's apparatus, like Quinet's, used electric light, and was shown to the Paris Photographic Society in 1861.

Demise

By 1890, artificial light sources – gas, petroleum, limelight, magnesium and electric light bulb – were commonly used in enlargers, so when, that year, Josef Maria Eder installed a Wothly solar camera on the roof of Vienna's Höhere Graphische Bundes-Lehr- und Versuchsanstalt the students would have considered it a vintage curiosity.

Even at the turn of the century simple folding daylight enlargers still found a use amongst amateurs to easily produce prints of a fixed size; one made by Griffin and Sons to enlarge quarter-plates to whole plate size, with achromatic lens built in, was 12s 6d (£60, or $US80 in 2020). Some cameras were made convertible to use in a similar manner.