T

Definition: (1) Time: usually in reference to camera shutter setting. (2) Time exposure: the shutter is opened on the first full pressure on the shutter release and stays open until the second press on the shutter button. See bulb exposure. (3) Transmittance. * See also T-number. T for tau? Actually T for transmittance is a mis-reading of the Greek capital letter tau 't' (which is hardly surprising), that the Powers That Be had decreed to be the international symbol for transmittance. But don't confuse this with T-number, which is indeed pronounced 'tee-number'.

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