zero in on

Aim precisely at a target, as in They zeroed in on the last snipers . [c. 1940]

Converge on, close in on, as in The children zeroed in on the electric train display . [Mid-1900s]

Direct one's attention to, concentrate or focus on, as in We must zero in on the exact combination of ingredients , or The whole class zeroed in on the new assignment . This usage transfers aiming a firearm to directing one's attention. [Mid-1900s]