Basically, a lens with a T-stop of 5.6 allows the same amount of light through as a theoretical f/5.6 lens with 100% transmission (0 reflection loss. 0 absorption loss).
Basically, a lens with a T-stop of 5.6 allows the same amount of light through as a theoretical f/5.6 lens with 100% transmission (0 reflection loss. 0 absorption loss).