T number
noun
,
Photography
1.
one of a series of calibrations of lens openings according to the intensity of the light actually transmitted by the lens.
Symbol:
T.
British Dictionary definitions for
T number
T-number
noun
1.
(
photog
) a function of the f-number of a camera lens that takes into account the amount of light actually transmitted by the lens
Word Origin
from
T
(
otal Light Transmission
)
Number