Re: large scale Baird/Nipkow Televisor project "Big Paul"
Posted: Tue Mar 14, 2017 2:08 am
Hi Gebhard,
As you probably know, the Baird company set up a mechanical 240-line flying spot camera at Alexandra Palace at the very start of the BBC Television Service. This used a 4-spiral 60-line disc rotating at 6000 rpm in a vacuum chamber, with a rotating shutter to select each spiral, one at a time.
Windfall Films Ltd originally wanted to reproduce this for a programme to mark the 80th Anniversary of British television. I supplied a Feasibility Report (attached here). They soon gave up, and made a 60-line rig instead!
It will be very hard to do this effectively with just one Nipkow spiral. But then, if you use more spirals with a shutter, the rim speed on this large disc goes up stll further! As others have said, the problem is going to be the tiny size of the holes required. To which I would add also: the precision needed in the positioning of the holes. If they are not spot on, the picture quality will be inferior to a lower line count.
If you can visit us at the Convention on April 8th, you will see demonstrations of 96-lines and 120-lines using various techniques. Even this is 'pushing it'...
Steve O
As you probably know, the Baird company set up a mechanical 240-line flying spot camera at Alexandra Palace at the very start of the BBC Television Service. This used a 4-spiral 60-line disc rotating at 6000 rpm in a vacuum chamber, with a rotating shutter to select each spiral, one at a time.
Windfall Films Ltd originally wanted to reproduce this for a programme to mark the 80th Anniversary of British television. I supplied a Feasibility Report (attached here). They soon gave up, and made a 60-line rig instead!
It will be very hard to do this effectively with just one Nipkow spiral. But then, if you use more spirals with a shutter, the rim speed on this large disc goes up stll further! As others have said, the problem is going to be the tiny size of the holes required. To which I would add also: the precision needed in the positioning of the holes. If they are not spot on, the picture quality will be inferior to a lower line count.
If you can visit us at the Convention on April 8th, you will see demonstrations of 96-lines and 120-lines using various techniques. Even this is 'pushing it'...
Steve O