One of four diapositive photographs in passe partout frame showing the Moon, originals taken by Warren De La Rue using the Kew photoheliograph.
Photographic glass slide, taken around 1858-1862, showing the gibbous phase of the Moon at last quarter. The picture taken by Warren De La Rue (1815-1889), a pioneer of astrophotography, was obtained using his 13-inch reflecting telescope at his observatory at Cranford, Middlesex. This was a difficult task, as the then available wet collodion plates were insensitive to light compared to modern films. This required exposures of several minutes through his telescope using a clock-driven equatorial mounting.