Assertion: lens | /r/HasAspect | focal length of 0.84
Facets:
value: in its original form
type: OTHER
value: in 21 mm
type: OTHER
Source sentences:
text: The Hill Sky Lens was fitted to a whole sky camera, typically used in a pair separated by 500 metres (1,600 ft) for stereo imaging, and equipped with a red filter for contrast; in its original form, the lens had a focal length of 0.84 in (21 mm) and cast an image 2.5 in (64 mm) in diameter at f/8.