Quote:
Originally Posted by Grubhead
There is actually no such thing as a 16.9 picture. All transmissions from broadcasters are 4.3. To make them 16.9 they use an anamorphic process, which as Brian says makes the 4.3 picture elongated. You simply get a wide angled lens then focus it on a smaller area. Then you get another lens then refocus it back. Or that's how they did it in the movies! In TV terms they squash the image on to the 4.3 frame. They then have a signal built in, which makes a 16.9 set switch to widescreen, and is switched off for standard 4.3 transmissions, which are not squashed. In fact some Sky channels frequently get this the other way around!
The other way is to add the black bars to the standard 4.3 transmission picture so it is framed right. Then send a widescreen signal to a TV to switch it to the zoom settings.
Depending on the age of the 4.3 TV, some have settings to switch the elongated picture to 4.3 or a zoom setting. Very old models will not have it at all and will show a elongated picture, or a black box all the way around.
It's a bit like trying to get shut of the black bands on a 21.9 picture on a 16.9 set. You can sometimes Zoom in, but you will loose some of the picture. Or you put up with the two black bars!
By the the way isn't 4.3L meaning 4.3 letterbox?
So if you want to loose the box switch it to 4.3 only.
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If I may I'm not sure your first paragraph is altogether accurate nowadays. The process you're describing (anamorphic compression) was what we used in broadcasting in the days of 4:3 / 16:9 625 line pictures (no other country in Europe used that system I believe). If you stood near the camera when it switched between the two aspect ratios you could hear a dull sort of 'chung' noise as the additional anamorphic lens was switched in or out of the optical path in the zoom lens package itself - not in the camera. I was working on Ikegami CCD cameras, other manufacturers may have used different techniques to get the same end result.
Since the introduction of broadcast 1080 HD pictures, cameras have always been fitted with native 16:9 sensors as that is the aspect ratio they work in, I do not know of any native HD camera that can switch between 4:3 and 16:9 as 4:3 is an obsolete TV production format.
We still TX a right old mixture of archive programmes so they need to broadcast aspect ratio information for the receivers to deal with - as you say, it is sometimes not as successful as it should be!