>>20398595About the apparent vignetting, it's not: it's preferencial reflectivity of the solar light by the microfractured minerals in the moon dust: notice that the ground is brighter AWAY from the sun's direction, where the most microscopic cleavage planes of all the microscopic mineral fragments are reflecting the light towards the camera, like microscopic mirrors.
Also, the closer you look towards the direction of the sun, less and less of such micro cleavage planes are oriented in the direction needed to reflect light directly at the camera, until the effect culminates when looking directly at the sun, where most cleavage planes are not oriented as necessary to reflect the light back at the camera. The effect is obvious in the landscape, and on the reflection in the visors, just as shown in the video.