A harvester includes an auger tube having a first portion and a second portion adjacent the first portion, an auger flight within the first portion of the tube and terminating prior to the second portion to move grain to the second portion, a window along the second portion of the tube and a camera to capture images of grain within the second portion of the tube. A computing device determines grain mass flow based upon the captured images, a dimension of the second portion of the tube and a grain density factor.
