Assertion: iron sight | /r/CapableOf | keep the whole
Facets:
value: at different distances
type: OTHER
Source sentences:
text: Iron sights take considerable experience and skill in the user who has to hold a proper eye position and focus exclusively on the front sight, keeping it centered on the (unfocused) rear sight, while keeping the whole centered on a target at different distances, requiring alignment of all three planes of focus to achieve a hit.