question about early color tv

[oldtvman]

Originally Posted by kx250rider

The early CRTs had sulfide phosphor, which caused the greens and reds to be much deeper. After the mid-50s, they went to rare earth phosphors, which made less-deep greens, and orangish reds.

Charles

With the sulfide tubes you really couldn't turn the brightness up all the way or the reds would appear orangey. The rare earth phosphers resolved a lot of those problems, but all the sets I see on this site have the contrast cranked and that was never the way to achieve the best possible picture.

If you look at some of the new flat panel with the THX settings they really cut back the contrast and brightness to take advantage of the visual effects of the film, the same could be said of the older color sets if you back down the contrast you really start seeing the beauty of the product.

[old_tv_nut]

Originally Posted by oldtvman

With the sulfide tubes you really couldn't turn the brightness up all the way or the reds would appear orangey. The rare earth phosphers resolved a lot of those problems, but all the sets I see on this site have the contrast cranked and that was never the way to achieve the best possible picture.

If you look at some of the new flat panel with the THX settings they really cut back the contrast and brightness to take advantage of the visual effects of the film, the same could be said of the older color sets if you back down the contrast you really start seeing the beauty of the product.

Yes, the sulfide red actually shifted toward orange at high current density. The rare earth red doesn't shift, but the sulfide green and blue can saturate at high current, which can be a problem in rear-projection sets.