Originally Posted by GeneraLight
1.) Do HDTV CRTs have input lag?
What is commonly called "input lag" probably should be called "display lag", since the delay (in question) is introduced after the input port of the TV and prior to display. The (total) delay/lag you encounter when you enter input on a game controller and see the results on screen is partly due to the response time of the game console, where the term "input lag" would be more appropriate.
In comparing a common signal to a Sony 30XBR910 (the CRT HDTV) versus a Sony 27XBR15 (from 1989), I was able to measure
a difference between the two TVs. The image capture was low-resolution and at only at 15 frames per second, but I compared a moving object relative to a stationary object on each screen, with the two TVs side-by-side. The image on the HDTV seems to be delayed by about one frame time as compared to the SDTV. The frame time and the delay time being similar (about 67 milliseconds) is probably a coincidence.
I'll leave it to the reader to make any generalization at their own risk.
2.) I heard that all HDTVs, including CRTs, use digital processing. Is there a way to completely bypass this processing to eliminate all input lag?
But it might be interesting to test/measure a TV such as the 4:3 Sony HighScan models (e.g. 3xHS510) that display 4:3 SD content full screen, but 16:9 content is "letterboxed" by compressing the 1080 interlaced raster lines. Perhaps the SD content has minimal processing (hence minimal delay) since the image is not being upscaled (to 1080i like on the XBR910).
3.) Do HDTV CRTs have native resolutions?
Monochrome CRTs (e.g. "black & white" TVs and 3-tube CRT projectors) do not have a "native resolution". A monochrome CRT has a clear path between the electron gun and phosphor screen, so the number of pixels that can be displayed is essentially limited by the bandwidth of the electronics & tube(s), beam size and the phosphor grain.
A color CRT has a screen composed of a mix of red, green and blue phosphors, arranged in dot trios or stripes. A shadow mask or aperture grille is positioned between the electron guns and the phosphor surface so that each gun will only activate its matching color (e.g. the electron gun for "blue" can only strike the blue phosphors and is blocked from the red & green phosphors). The resolution of the input video does not have to exactly match the display (like a fixed-pixel display) or else be scaled to do so
, as long as the electron guns can turn on & off within their bandwidth. But there is an optimal resolution since there are discrete pixels visible on the color CRT's face. Ideally the resolution of the signal matches one-for-one the "native resolution" of the tube, as dictated by its dot pitch
. If the signal resolution does not match up to the dot pitch, then more or less (phosphor) dots are or are not lit up. Each gun (for each color) just turns on and off per the input signal, and there's no harm or foul if the beam is on for more than one (phosphor) dot (or less than one dot). (Fixed-pixel displays do not have it simple; each pixel has to be individually addressed and controlled, hence the input resolution has to be scaled to exactly match the panel.) Some CRT HDTVs, such as the xxXBR910, upscale all input to 1080i with excellent results in order to reduce visible scan lines of standard NTSC displays.