Camera obscuras used to form images on walls in darkened rooms; image formation via a pinhole
Brightness and clarity of camera obscuras improved by enlarging the hole inserting a telescope lens
Camera obscuras in frequent use by artists and made portable in the form of sedan chairs
Professor J. Schulze mixes chalk, nitric acid, and silver in a flask; notices darkening on side of flask exposed to sunlight. Accidental creation of the first photo-sensitive compound.
Thomas Wedgwood makes "sun pictures" by placing opaque objects on leather treated with silver nitrate; resulting images deteriorated rapidly, however, if displayed under light stronger than from candles.
Nicéphore Niépce combines the camera obscura with photosensitive paper
Niépce creates a permanent image.
Henry Fox Talbot creates permanent (negative) images using paper soaked in silver chloride and fixed with a salt solution. Talbot created positive images by contact printing onto another sheet of paper.