释义 |
t-number \ˈ ̷ ̷ˌ ̷ ̷ ̷ ̷\ noun Usage: usually capitalized T Etymology: total light transmission + number : a number that is similar to the f-number but takes into account the amount of light actually transmitted by a lens after loss by absorption and reflection and that equals the f-number divided by the square root of the transmittance |