I've noticed that in many launch live streams the count down clock disappears from the screen shortly before liftoff.
ULA seems to remove the clock at T-30 seconds. NASA streams also seen to remove it around that time, but not exactly at 30 like ULA.
However, both Arianespace and SpaceX keep the clock visible.
Why do some providers remove the clock, and why at around T-30?
Did I post this question in the wrong place? Or is there just not a well known reason for the difference?
Here's my guess. It makes for a cleaner launch video that news organizations can show and that "print" news can capture. Even back in the early Space-Age days, newspapers used to use photographs of TV broadcast images of launches to provide a timely image for the morning paper. Today, web sites do the same thing, in effect, in order to get an image up quickly. It sometimes takes hours or days for the official launch images to be posted, by which time the launch is old news.
Arianespace posts launch images almost instantly, making it easy for news folks. NASA and Roscosmos provide clean video. SpaceX provides badly cropped prelaunch images and launch video, making it harder. ULA and ISRO, with their giant ugly "crawls" hiding part of their launches, don't want to be in the news at all, apparently.
- Ed Kyle
Interesting. So it might be purely for having a clean image for news organizations to use?