Unfortunately, I don’t have any Python code yet because my own project has been progressing rather slowly lately (as life gets in the way … I’m sure many here are all too familiar with the phenomenon 
).
I’m glad to see @dgalland has shared his code already. Maybe the question generally warrants a one-place-to-go-to thread where people can link and discuss Python code they use for capturing frames (much in the same spirit as the Scan Examples of Super-8 material thread)? It might allow others (myself included when I finally get there ) to find information on the topic in one place.
P.S. The photos from my experiment above were taken using the raspistill command. You could, in theory, call this from a Python script … but please don’t! 