Quote:
Originally Posted by red16v
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!
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As far as I am aware the transmission of TV shows is still done in the 4.3 format. The pictures might be shot on a 16.9 camera. But if you switch the TV picture to 4.3 you get an elongated picture still. There is a signal inside this 4.3 signal that makes the TV switch to the 16.9 angle. When a 4.3 picture from an old TV is shown, the TV doesn't switch to wide. By still using a 4.3 image size, even on HD, you can keep the signal size considerable reduced and therefore have more TV stations. Otherwise you would finish up with a very large signal and also require different sets.
Just a little background on aspect size. The original size of a cinema screen was 1.33 or 4.3. Then later bands were placed on the top and bottom to accommodate the sound on the same film. This became known as Academy Ratio or 1.37. When Television came out they adopted the 1.33 ratio of the film industry. In fact if you look at some pictures of 1920's picture place screens they look like they have got a giant TV set! Even down to the curved edges! Later on the TV industry adopted the 16.9 or 1.78 widescreen as a compromise between the much higher 2.35 of the Panavision system used on the larger screen movies.
However most of the widescreen movies were shot on 35mm film which gives the 1.33 or 1.37 picture. To get around this they used an anamorphic lens, which when reversed gave the widescreen pictures of 1.85 (standard) and 2.35 ratio. Larger types of film gave rise to formats such as Ultra Panavision etc.
1920 picture screen