I’ve been with @kueda when he’s used that lens (which is really really difficult to use) and he uses a twin flash (I think the Meike one now? but I could be wrong). Here are some obs where I think he used that set-up:
https://www.inaturalist.org/observations/142416962
https://www.inaturalist.org/observations/70803811
https://www.inaturalist.org/observations/70803802