Constitution Hill, Aberystwyth, Wales.

It is run as part of the : 
Aberystwyth Cliff Railway
Cliff Railway House
Cliff Terrace
Aberystwyth
SY23 2DN
United Kingdom

Tel: 01970 617642

There was originally a camera obscura, with a small 4" lens, at Aberystwyth Castle in about 1880. This was rebuilt on Constitution Hill in about 1896 but it was gone by the 1920s. New optics were made by Pilkington PE Ltd. of St. Asaph, Clwyd. The present camera obscura is in a purpose-built two-storey octagonal tower adjacent to the site of the Victorian building and it was opened in 1985.

The lens is 14" in diameter but is stopped down to 12 1/2"and has three elements (a triplet). The focal ratio is F20 with the focal length at 6.4 metres. The screen is 52" in diameter and the field of view is 10 degrees. With this equipment the harbour and town of Aberystwyth can be viewed as well as the mountains behind the town.