[Daryl]

Daryl,

It looks like there is some rolling of the ball on the face during the compression stage. You can see it in the driver and 3 iron photos. Look closely at the logo and ball # and you'll see a slight upward tilting of the ball during compression. Its very, very slight but shows the ball does change its polar axis during impact. Its not just a direct rebound off the clubface from a decending clubhead blow.

This action might explain why sharper grooves help keep the ball in its original axis thereby increasing spin.

Then again, these photos might depict impact after lowpoint.

Just guessing.

great observation.

The impacts are before Low Point.

I can see the name tilting as you describe. I couldn't tell whether that's from rolling or straight forward deformation. But the spin (rolling) is much more obvious as the ball leaves the face of the club.

Tonight I'll include photos of a Wedge and 7 iron.