瞬間

1. Origins, structure, and basic meaning

• Structure: 瞬間 (しゅんかん) is a noun for a very brief moment. It can locate a following event in time or name a moment captured as an object.
• Basic usage: 扉を開けた瞬間 fixes when the cold wind entered; 鳥が飛び立つ瞬間を names the instant captured in a photograph.

2. Common pitfalls and similar expressions

• Time of a following event and instant captured
  • The first 瞬間 behaves like a temporal link modifying what follows; the second 瞬間を is the object of photography. The duration sense stays constant but the constituent role changes.