To zoom in is to make a view closer and larger. Zoom in on the detail, zoom in a bit, zoomed in too far.
Optical zoom moves the lens and digital zoom simply enlarges the pixels, which is why one keeps the detail and the other does not. The figurative use means to focus attention narrowly.
1phrasezoom inTo make a view closer and larger.
“You can zoom in on the map to see the names of the smaller streets.”
zoom in is a magnifying.
Zoom plus in, from the sound word zoom applied to a lens that moves.
From zoom + in.
Etymology from Wiktionary, CC BY-SA
Practised in Ways of Looking