Origins of the 405 line system.

[ppppenguin]

I agree that pedestal is the technically correct name for the difference between black and blanking levels. I have often heard it colloquially called lift and thought you meant pedestal. I'm not sure where lift was manually controlled in the M-EMI programme chain though it must have been individually controlled for each camera by the racks operator.

The racks operator had a difficult job in the early days. Quite a apart from the ill defined black level from early camera tubes, the tilt and bend controls would have been difficult to optimise, especially if the lighting was less than ideal. One of the reasons why the M-EMI telecine wasn't very good - coping with rapid changes in average picture level was hard.

PS: "There was no reason that the Baird system couldn't support mixing" Apart from the fact that the Baird studio had just the FS and IFT cameras plus a telecine. Even if they were synchronous, mixing would have been a nightmare. Made worse by the fact that the Baird system made no attempt to stabilise the black level. This may have been due to patent problems or not having circuit designers of the calibre of Blumlein and his colleagues.