Hi Dean.
You are quite right. using standard AV equipment, we can get results down to 20ms using PAL format equipment. That's one fiftieth of a second.
PAL records at 25fps and each frame can be separated into 2 fields (the format scans all the odd numbered lines then all the even numbered lines (or vide-versa))
Of course NTSC is 30/60 fps.
Our biggest issue is simply the brightness of the target! That's where aperture and location rules. So on a good night you can recoded events like this:
https://www.youtube.com/watch?v=lSyMu0l75zQ at max rate. In this case, the non-immediate disappearance suggests that the star may be a contact binary. You never know what you will discover during an occultation and that's what keeps us going
It is possible to get even higher frame rates with other video devices, but getting a good timing signal becomes the main issue. Thankfully we bow down to Tony Barry for being our resident electronics expert who has made so much of this possible in recent years
