Assertion: lens's number | /r/CreatedBy | camera manufacturers
Facets:
value: over the years
type: TEMPORAL
value: by third-party optics companies
type: OTHER
Source sentences:
text: Film SLR cameras have existed since the late 1950s, and over the years a very large number of different lenses have been produced, both by camera manufacturers (who typically only make lenses intended for their own camera bodies) and by third-party optics companies who may make lenses for several different camera lines.