Photoshoot at UBC Tower beach

Just want to share another picture here. Marc mentioned that we can talk about it when we have the flash class. This was shot last summer with my girl friend at UBC Tower beach. We waited for the sunset to capture that orange shade in the middle.

External flash at almost direct angle towards the subject. ISO 500, 1/160, and f6.3. Was using P mode, but could probably use a better combination of these now.

Marc - what's the ideal combination of ISO, S speed and F no. in these situation?

I definitely want to learn more about the settings in the external flash. THANKS.