CurtPalme.com Home Theater Forum

[cmjohnson]

I figured the day was going to come when the venerable CRT projector was going to be eclipsed, at least in resolution capacity,
by newer digital display systems.

That day has arrived with the advent of 4K HD.

I'm not confident that even LUG tubes with optimized Frankyoke Mark IIs have the resolution capacity needed to resolve
4K at an MTF value that's worth mentioning.

I'm pretty confident that the best lenses on the market (GT17s) MIGHT be able to resolve the image IF you can get that
resolution on the CRT face as the HD10GT17 lens is rated to resolve 12 line pairs per millimeter, and assuming your raster height is 4 inches, which is 101.6 inches, then you would have a line density of 9.8425 line PAIRS per millimeter. (4K
being 4000 x 2000 resolution, or 4000 x 1000 line pairs.)

So we MIGHT have a tube that can do it. (Don't know the minimum possible spot size of a LUG tube.)
We apparently DO have lenses that can (theoretically) do it.

We MIGHT have focus yokes (after modification) that can do it.

But we don't have the video chain bandwidth to do it.

That 4K signal in a CRT projector eventually has to be broken down to video drive signals that change the intensity of the
flying electron beam up to 8 million times per frame, and maybe up to 60 frames per second if not more, eventually.

As per an article from cnet:

[jeffslife]

At my local video store only about 40% of the titles are available in blu ray. That number last year was about 20%. A lot of people don't even own a BD player. I cant imagine 4K being viable when BD hasn't even become mainstream yet.

[tschaeikaei]

Did you think about going interlaced?
I don't know if the framerate of 4k blu ray disks is 24 or 23.9xxHz, but if you double that number, you'll get 48Hz (or 47.xx).
That's 2160*48/2=51.8kHz, add porches and you are at about 55-60KHz.
Good to handle on every higher end machine.
The bandwidth needed would still be high: 3840*2160*48/2=199MHz, 260MHz with a porches-factor of 1.3.
But that should be achievable.
I read from Mike Parker, that a 9500 Ultra should (after modding) easily do 240MHz, that's not far from 260.
Noos37XP did 4k interlaced on a Sony HDIH (best lenses and "resolution king", as he said)
and on various other projectors. There are videos on youtube.

But my personal opinion (or guess) is that 48Hz is not enough for a watchable picture.
Not on a fast green tube. On the normal P22 green it should be fine.
But if it's interlaced, you will maybe get lots of motion blur.
But... you do have a high end CRT projector?
Try it.
Regards, Julian

[tschaeikaei]

[Nashou66]

Only if you blend,

https://www.youtube.com/watch?v=iZdzBNPfq8E

[km987654]

[km987654]

[stridsvognen]

I think that downscaling is the only solution.

Get the best downscaling to 1920x1080P 60-72hz, hope 4K will be a higher native framerate, and less compressed, with better bit dept.

There is only some modified Marquee machines who resolves a decent 1080P 60hz, so why even think about pushing 4K on a CRT.?

Will it be possible on a blend.? sure.. but only displaying it, not resolving it, and if you cant resolve it, whats the reason.?

Who run 1080P 60hz on a 7" CRT projector, and why not.?

[redfox001]

One thing to add to this discussion is the question if 4k will give a better image on CRT anyway. On led tv they say it reduces the screendoor effect and it is only noticeable close to a screen.

So before having a 4k problem I would like to know is there is a visible difference.

One thing to make me feel comfortable with 1080p is that I have seen 4k tv's with normal material and they looked terrible and the best demo material on a 4k looked the same as my 1080p led tv when I took some distance from it. The 4k screen happened to be a very large screen for obvious reasons to make it noticeable with only the best demo material.

On the other hand I see that increasing the bandwidth on a Cine 9 makes the image almost as hard as digital. Do I like that??? It starts to look like video. I don't know if you guys know what I mean. Less filmish.

To sum it up. I am not convinced yet of the vallue of 4k. But I do enjoy 720p material almost as much as 1080p so perhaps I am not critical enough

[stridsvognen]

[redfox001]

Why is that curious? You have seen the one on one pictures. Might be that I don't understand it yet but if the colour difference becomes less than there is more bandwidth not? How can you even argue with this without denying one of the premises. Was there not less colour difference? Did this not proof the bandwith went up?

The rest is subjective of cause and I don't want to say I am certain that higher bandwidth will not improve the picture or that 4k will not be an improvement. I don't know that yet.

[stridsvognen]

[redfox001]

Ok good point. I have to agree I changed hardware and setup focus etc. So I am not certain what made the picture a little hard/unnatural in my feeling and it might be that after another setup I agree that the higher the bandwidth the better I hope so!

[cmjohnson]

I have been out of the loop for a while, so to speak. Not really paying attention to this forum.

Please point me to information regarding the latest high bandwidth MP video chain mods. I may be very interested in pursuing them.

[digitalayon]

Still tons of theaters are only 1080p and not 4k. 4K is really only going to be flat panel for the most part for the next 3-4 years......so enjoy your PJ.

[jbmeyer13]

[ecrabb]

[JayAllan]

[Spanky Ham]

As you said, I thought everything was shot in 4k, but I thought downrezzed (?) after that. Are they archiving everything at 4k? Unless it has changed recently, my best friend said that CGI/animation was done at 1080p.

[ecrabb]