AE will handle any frame rate for source footage but has a 99 FPS comp frame limit. So what does this mean to you.
First of all, I have shot film and video up to 30,000 frames per second, but I've never seen it played back at that rate. The main reason for high FPS footage is to generate smooth slow motion. You shoot at 240 playback at 24 and one second of real time takes 10 seconds to playback. If you could playback at 240 then the playback would take 1 second and your eye couldn't tell the difference between that and footage that was shot at 24fps and played back at 24.
There's not a playback device that I know of that's capable of playing back your movie at 210 frames per second. If the clip is 10 seconds long @ 210 fps and you import it into AE and set the time display to frames you'll see that you have all 2100 frames. You can work on the frames, then export them, and let the playback device play them back at any frame rate the device is capable of.
I hope this answers your question.
Thanks a lot. I will try this. Thank you for a very helpfull advise.