Roundies (top & bottom of screen covered)

[Aussie Bloke]

Hi all. I've been meaning to ask this question for a little while. With the round tube colour TVs (and B&W as well), why are the tops and bottoms of the picture tube covered when the whole tube could be utilized to give a full porthole picture? I'm curious because I've seen on Ebay and sites B&W TVs that utilize the whole tube which I guess are referred as "porthole sets" and I thought wouldn't it be better for the viewer to see a bit more picture by utilizing the whole tube without covering the tops and bottoms? I wonder if the reason is a fashion thing where the TV would look neater like they are or whether the designers back then wanted the sets to look as rectangular as possible?

Must admit when I first saw a roundie on that Freddie Kruger movie which had blood oozing from it, I thought that was the shape of the picture tube, didn't realise that the tubes were circular til only a few years back when I first looked at old TV sites on the net.

Anyways the only porthole colour TV I seen is that home made tube tester set one of you guys showed in recent months which some bloke would of built which has a 60s CTC chassis of some model and tubes are fitted and tested.

I just wonder if any porthole colour TVs were ever built?

Cheers
Troy

[Chad Hauris]

Yes, I think they wanted to make the picture appear as rectangular as possible...also the mask around the round tube is often painted the same color as the tube (when off) to further try to disguise the roundness of the screen.

There are some b/w sets where the mask is actually totally rectangular over a round tube...cropping the sides as well as the top and bottom.

[bgadow]

Westinghouse in the late 40s or so had a "convertible" model that could be a porthole or you could make an adjustment & the top/bottom would be masked off. I'm sure there are some pics on this site of one. Some of the Zenith bw portholes, I think, had a button where the picture would be reduced in height so that it had a flat top/bottom. I think folks were so used to going to the movies when tv came out that they expected a rectangular picture and a round one was just odd; some companies, Zenith most notably, gambled that people would prefer the round (and larger) screen. By the time color roundies came out bw sets were all pretty rectangular so it really would have taken some getting used to.

[andy]

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[Eric H]

I would think the main reason for the masking is to maintain the correct 4:3 aspect ratio. A porthole set would require cutting more off the sides.

[ceebee23]

do roundies handle the fact that scan lines are of differnt length as the beam moves down the screen????

mmmm.....