This is why cinema lenses report t-stops ('transmission') in addition to f-stops. The t-stops tell you about exposure, and account for losses between surfaces a

This is why cinema lenses report t-stops ('transmission') in addition to f-stops. The t-stops tell you about exposure, and account for losses between surfaces and absorption within the media. The f-stop tells you about depth of field, etc. With modern lenses, they're usually within a small fraction of a stop, but older lenses could vary by a stop or more. That said, the difference between this camera and an iPhone camera, in terms of relative transmission, is probably negligible.