CinemaScope

Not really sure if this is related with television, but does anyone know the 'screen ratio' of CinemaScope films/movies?

I am asking this because BBC Two were showing the film "A Star is Born" over Christmas and I, knowing it was CinemaScope, knew it wouldn't be cropped on my widescreen (16:9, obviously) television - but I recently bought the DVD box set and the picture had large-ish black bars at the top and bottom of the screen. Because of this, the action went on much further at the left and right-hand sides of the screen.

Wikipedia comes up trumps as usual. There's a page about it here:

http://en.wikipedia.org/wiki/Cinemascope

Most widescreen DVDs are either 1.85:1 (16:9) or 2.35:1 (deep black bars).

When CinemaScope originally launched in 1951 the projected ratio was 2.5:1, however very few cinemas could comfortably cope with that as until then proscenium openings had mostly been designed to take into account the 1.33:1 'Academy' ratio, so were far too narrow. 'Scope settled into the now standard 2.35:1 ratio soon afterwards, even so many smaller cinemas either had to have expensive building alterations, 'floating' screens, or put up with a real letterbox! In many older houses there wasn't room for the side masking to open out, so the top masking came down, thus giving a smaller picture area than either 'Academy'(1.33:1) or 'widescreen' (originally 1.75:1 now universally 1.85:1) leading to similar complaints to those watching deep-letterbox on a small 4:3 TV screen!

CinemaScope is a true anamorphic format, using the full height of the 35mm frame and shot with an anamorphic lens to compress the horizontal axis. The projector is fitted with the reverse anamorph to open out the picture again. However 'widescreen' (1.85:1) is in fact a letterbox format. The full 35mm frame is used, but the picture is composed in the vertical centre of frame, the top and bottom being masked by the projector's aperture plate, thus creating the impression of a wider picture.

It the scene in 'Dirty Dancing' where they're on the bridge over the ditch, if you 'rack up' the projector you can see the boom operator lying in the bottom of the ditch!!