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Does anyone here know exactly when 4:3 became the standard aspect ratio for TV sets? Must have been earlier than 1950, at least 60 years ago. The math there is interesting, because 4:3 corresponds to the 3:4:5 ratio of a right triangle pythagoras theorem. That is, 3 squared is 9, 4 squared is 16 and the sum of those is 25 which just happens to be the square of (tada), 5!
That means, among other things, that if 4:3 had survived into big screen flat panels, a 50-inch diagonal flat panel would be exactly 30 inches high and 40 inches wide.
But now we have 16:9. That is no obvious ratio, it is often rounded to 1.78, but that isn't even accurate except to two decimal places. The problem is, film-makers dont film in 1.78. They film typically in 1.85 for "standard" movies, but wide-screen movies are typically 2.35 aspect ratio.
16:9 math gets more complex. For our 50-inch diagonal screen, its helpful to divide 2500 by 337, and then take the square root of that. The 2500 is 50 squared. Interestingly, 337 is the sum of 16 squared (256) and 9 squared (81).
The resultant number from this math multiplied by 16 gets you the width of the screen, or when multiplied by 9 gets you the height of the screen. YOu can of course use the same approach for other diagonal measurements, just square the diagonal measurement you want to use, and divide by 337. Then take the square root of that number to get your factor that gets multiplied by 16 or 9 to find the width or height.
A widescreen movie to DVD transfer typically will be at minimum 1.85, and often 2.35. Even the widescreen 1.85 results in small black bars at the top and bottom. In my large DVD collection, I've run into exactly 1 widescreen DVD that claims to have been redune to fit exactly 1.78, the movie "White Palace". The rest of the widescreens are either 1.85 or commonly 2.35 which results in fairly wide black bars on my 16:9 projection screen. I can fill the screen with the DVD player or projector zoom, but I lose the stuff on the edges then.
Meanwhile I go to the theater and am constantly watching them jockey around with power screen top and bottom or side curtain pulldowns and pull aparts to adjust the apparent height or width of the screen to fit what they are showing, the previews are typically 1.85, but the feature most often is 2.35. Many in the audience dont even seem to notice the foolishness.
Then occasionally the projectionist goofs and flips on the wronng anamorphic lens, which typically results in very tall and skinny actors.
In the 60s and 70s there were experiments in making widescreen movies on 70mm not 35mm film, but silver oxide film technology improved and it was cheaper to film everything on conventional 35mm film, using camera lenses to scrunch everything together horizontally, and then to have a anamorphic reconversion lens on the projector at the theater to unschrunch everything back to widescreen. Certaionly cheaper than having a different projector that could run 70mm wide film for the occasional movie filmed on 70mm for sure.
As I sit in the theater and watch all these gymnastics, from cheens changing aspect ratios at the flip of a button to projectionists who mistakenly run the 1.85 lens on a 2.35 movie, and think to myself that most of the time all these goings on work more or less flawlessly.
Follow Ups:
The 4:3 aspect ratio was picked by Edison's people, back in the 1890s. The standard just stuck, and tv carried it on. Hollywood started making wide-screen films in the mid-fifies, well after the NTSC tv standards had been set at 4:3.
In Europe the standard film format is 1.66 instead of 1.85 like here.
16:9, at 1.78, was a compromise between the European and US standards.
Also I believe the 4:3 aspect ration is determined by the typical size of the 35mm film frame size. Later wide screen film simply split the 35 MM frame size in order to get the wider screen.
Then again, not many may remember the 35 mm film cameras....
Stu
The 35mm frame size is 36mm wide by 24 mm high. That's 3:2 and that doesn't match either screen proportion of 4:3 or 19:9, nor does it match 1.66:1, 1.85:1 or any of the really wide screen ratios like 2.35:1.
David Aiken
Film 35 MM had some space allowed for the audio soundtrack, thus limiting the full use of the 24 mm width. I believe the standard aspect ration thus drops to 1.37:1, pretty close to the 4:3 ratio or 1.33:1. In addition the standard TV signal has 525 lines by 720 which similarly yields a 1.37:1 ratio, although normally only 480 lines are displayed.
I stand by my statement.
Stu
You said "Film 35 MM had some space allowed for the audio soundtrack, thus limiting the full use of the 24 mm width." Actually the width of the frame is the 36mm dimension and cutting that down to 32 mm would give you a 4:3 ratio so you're probably right there. I hadn't considered the need to allow space for the optical soundtrack and just reeled off the 35mm negative frame size from my old still photography days.Added comment: The above paragraph is as I originally wrote it. I've since realised that 35mm film goes through the gate of a still camera at right angles to the way it travels through the gate of a movie camera so you're right, the width of the frame is 24 mm which means I have no idea what the height of the frame is. I stupidly assumed that it would be the same for a movie camera as for a still camera and it isn't. I've left the original para in to show where I was coming from.
You also said "In addition the standard TV signal has 525 lines by 720 which similarly yields a 1.37:1 ratio, although normally only 480 lines are displayed." It's what's displayed that counts and 720 pixels wide by 480 high is 3:2, not the 4:3 physical dimension ratio. You can use pixel ratios as an indication of image ratios on widescreen TVs because 1920/1080, 1366/768, and 1280/720 all basically come to 16:9, at least to roughly 2 decimal places, but that approach definitely doesn't work for standard definition screens in either NTSC (720 x 480 pixel display) or PAL (720 x 576 pixel display).
But then again, standard def displays weren't created with digital image formats in mind. If they'd bothered to think ahead we'd have been watching cinemascope movies in theatres in the 1920s and wide screen TV when TV was first introduced :-)
David Aiken
I was just elaborating on the comments posted by the previous poster. Film's a different animal.
Being a history major, I get a little caught up in the historical triggers for certain standards.
Stu
since I go to few movies, (but watch many dvd's on my Sony HD tv), is the fact that a lot of dvd's have the movie is whatever widescreen format they are using, but the rest of the material in 4:3 aspect. Couldn't they at least try a little harder?
I've even noticed this when watching the MASH tv series on dvd, wasn't this only filmed in 4:3? I would think so.
Vacuum Tubes were made for audio, solid state for computers, please don't mix them.
...ever heard of the Univac computer? :o)
Cheers,
AuPh
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