Exactly. It's the standard measurement used for cinema lenses, it's the F-stop corrected for absorbance and reflectance. It is usually very close to the F-stop, I was just curious as to whether some manufacturers' lenses might be more affected by absorbance and reflectance than others. But I guess guess if the T-stop was never given by the manufacturer, it'd be pretty hard to figure out.
Originally Posted by MattKing