Capturing HG21 footy at '24pf'... 29.97 correct?

[MikeWilkinson]

I'm having a client shoot with an HG21 for b-roll, and I wanted it to match up with my HVX 720/24pn. The HG21 claims 24p native, but I capture the avchd and and it comes in as ProRes 422 @ 29.97. How can I capture it at 23.98?