I'm still a beginner in using flash. I have a question about bounce flash. I use a Yongnuo YN560 which is strictly manual. The bounce effect is only effective in places with a typical 10 feet ceiling. In places like large halls where the ceiling is usually 2-3 storeys high, I can't get enough light to bounce back to the subject on the ground. Getting that bounce effect is possible, but I have to use a very high ISO like 1600 to 3200 together with my flash set to maximum power. This consumes a lot of power and the high ISO is not so pleasant.

I'm wondering, I see many photographers, professionals also practice shoot in large halls with the flash firing pointing up. Did I miss anything here? Would using a TTL flash helps? Or simply my flash is not powerful enough?