glassing
n.— «For hours until sunset, he sits utterly still, using his Swarovski binoculars and spotting scope to scan for deer. “Glassing,” as it’s called, offers the boredom of fishing without the boat or the beer, yet it’s monotony with a purpose.» —“Hunting in a forbidding zone” by Deborah Sullivan Brennan Los Angeles Times Oct. 25, 2005. (source: Double-Tongued Dictionary)