Assertion: comet | /r/CapableOf | use a 7-second exposure
Facets:
value: with an f/2.4 portrait lens
type: OTHER
Source sentences:
text: Donati's Comet was successfully photographed on September 27 by W. Usherwood, a portrait photographer at Walton-on-the-Hill, Surrey, using a 7-second exposure with an f/2.4 portrait lens, the first time a comet had been photographed.