CurtPalme.com Home Theater Forum

[cmjohnson]

Go confirm this with Tse. He posted about it in his topic about the HR project.

What I say is very easy to predict in a thought experiment. Increasing contrast levels cause larger spot size and the simplest way to see this for yourself would be to use a digital camera with a lot of zoom range and take a few photos of the test patterns at several contrast levels. Even before obvious blooming you'll see the space between the line shrink and become less contrasty.

Don't argue with me, do the experiment yourself. Or think about the fact that the beam profile isn't ever a square wave, and the change to the power distribution pattern that MUST occur when you increase the amplitude of the signal. Even with perfect, scatterless phosphor, there's going to be a change in the excited phosphor area with increased contrast levels.

You could visualize this, very closely, if you were well acquainted with the usage of a spectrum analyzer to read the characteristics of a simple CW signal. As the amplitude of it increases, the width of the signal is observed to increase as well, at the chosen measurement level. Imagine the measurement level as being the representation of the phosphor layer of the crt. The beam profile MUST get slightly wider with increasing contrast levels simply because it is a Gaussian profile, not a square wave profile, when viewed spatially.

ONLY if the beam profile was a square wave AND the phosphor was scatterless would you have an MTF that is contrast invariant.

[tschaeikaei]

And this effect of loosing optical resolution (=bigger spotsize) using high contrast settings is always worried about especially on the Marquee.
That's why they all use the Frankenyokes. But just try yourself. Every CRT does it.
I would go and ask MP if his contrast 100 Marquee gets sharper when ramping contrast down.
But this really is obvious. You can even try it on an analogue oscilloscope CRT, same thing. Fuzzy when it's bright.
Maybe that's the reason (apart from the lenses) that the Sony HDIH has so good resolution. It just doesn't put out much light.
Regards, Julian

[Spanky Ham]

[cmjohnson]

I wasn't sure if you were questioning my assertions, or just asking for specifics concerning actual MTF values.

I don't (yet) have a way to measure those values but I am looking to change that.

I personally don't like to run at higher contrast levels. I want my tubes to last a long time, so I set levels that I am comfortable with. It may be a lower level than some people may like to run theirs at, but I watch in a fully darkened room and even then, the level is sufficient that a full brightness scene in a movie, like a sun shot, is enough to make me squint. Why would I want to run it any higher than that?

I am of the school of thought that says to set up the projector for razor sharpness, with clear definition in the scan lines, and then back off focus just enough to let the lines start to merge to get a film-like smoothness to the image. But actually I have something even better that I do. I play with the astig instead. I try to adjust beam shape so that it's shaped like ( | ) rather than like ( O ) and set the height of the scan line so that it just touches the scan lines above and below, while maximizing the horizontal resolution capacity. I think it has promise. I've tried it and BELIEVE I'm seeing a better defined image.

I invite you to try it for yourself. Tell me what you think.

[tschaeikaei]

On the Marquee and NEC PG, as well as on the ESF Barco, it is clearly visible. I'd call it a big effect. You can kind of minimize it by doing a very proper CPC magnets setup but it will always be very noticable. And yes, for me, high gain (combined with a blend for further improved bightness) is defenitely the way to go.
High gain will always improve the contrast ratio of a CRT projector. The blacks are still almost at zero and the brighter portions of the image will be much brighter than on standard gain 1 screens.
So the overall contrast is improved. You may have to tweak the gamma, but my setup is not completely done and i don't worry about gamma at this point.
But don't let people tell you, a silver screen would mess up colors. I defenitely got a wow-effect when i first fired the marquee onto my high gain screen.
Best thing si that the tubes will last much longer if driven at lower contrast.
Regards, Julian

[cmjohnson]

A silver screen doesn't have to cause color shift, but it has to have no significant amount of specular reflection in order to do so. (Specular = image forming. An ideal mirror is 100 percent specular, ultra flat white painted surfaces are zero percent specular.)

If I had a gain screen I'd probably run my contrast around 40. Or less. On a flat white screen I run 50, maybe 60 at most, and it's not due to any blooming issues, it's just because that's bright enough to make me happy and the tubes should outlast ME at this rate.

[tschaeikaei]

[cmjohnson]

Well, I do have a 3500 lumen InFocus LP840. It's good for up to 1080i, no guarantees about black level, though!

I should watch one movie on it before I decide to sell it or not.

[tschaeikaei]

§1 Digitals are to make geometry adjustments easier. That's it
§2 After completing the CRTs setup, put the digital into the bookshelf to prevent the books from falling over.
Regards, Julian

[Curt Palme]

[Curt Palme]

[cmjohnson]

One of my best friends is a pretty serious home theatre enthusiast. A few nights ago I went to his place and we watched a few movies in his almost complete theatre, which is NICE, as good as any you could pay a specialist company to install in your house for big money.

He used to use CRT projectors, a succession of them. Last one was a 9500LC.

Now he uses a JVC D-ILA (don't know the model, sorry) with an anamorphic lens and his screen width is in the general range of 12 feet.

I found the image quality to be more than acceptable. Black levels are excellent, and that's coming from a CRT enthusiast. Since I like to not lose details in the blacks, I tend to adjust for black to be the dimmest visible shade of dark grey, and his black level with that projector was right about there. Not perfect black, but really about as good as you ever see in a movie theatre OR a home theatre.

If I had to start from scratch and had the budget to do it, I'd probably follow my friend's lead and direction. But I'm not sure that I'd match him and install TWO Contrabass subs like he did.

It kind of distracts you from the movie a little bit when a pair of Contrabasses suddenly decide to knock you out of your seat and throw your popcorn on the floor!

[tschaeikaei]

Curt, i knew you would like this one
I don't see any point in those flamewars between digital and CRT users.
It's not about picture quality, it is about everyone thinking his horse is the fastest in the stable.
https://www.youtube.com/watch?v=fRW6Ky4sNM8 You'll know that song.
I've worked with motorcycles for about 10 years and i know those people. Everyone of them has the best bike in the world.
The thing between CRT and digital has an additional point:
Digital projector- guys are lazy. They hated adjusting all the things you'll have to if you want a decent picture out of a CRT.
If they had a CRT in the past, they never did astig, proper raster centering, toe in, scheimpflug..
And that's why they say CRTs are sh*t.
They hated working with gycol, were afraid of high voltage and simply didn't see the sport and competition that's in these things.
If you're not technically interested, CRT is not for you. I think it is that simple and always was.
There may be people without any technical interest and knowledge with a decent set up CRT in the past,
but those were the guys with thick pockets. Setting up the thing was making a phonecall and waiting until a specialist came by and did it.
I conclude that owning too much money makes people stay stupid.
And that is why you should not vote for the orange guy.
Regards Julian

[ecrabb]

[cmjohnson]

I think we can agree that to keep a CRT projector in top performance condition, you need to be a hands-on kind of person who likes to get under the hood and make adjustments. Or you need to work with someone who will do it for you.

Other than the obvious brightness issue, the best digital projectors and the best CRT projectors are still in a neck-and-neck battle for picture quality. And you can get 4K digital projectors today, though true 4K content is scarce at this point.

CRT projector manufacturing was at its peak at the end of the 1990s, more or less. It has taken more than 20 years for digital projectors to get to the point where a CRT enthusiast accustomed to top performing units can look at what digitals today can do and find little to fault. And only the highest ranks of digitals perform on that level. How many generations of digital projectors have our CRTs outlasted? I've lost count.

CRT projectors are also engineered to be durable, long lasting products. A 20 year old Marquee chassis is still perfectly good and
perfectly usable, with a little maintenance, if the tubes are good. But what condition is a 20 year old early digital projector going to be in today? If you can find a lamp for it, if the adhesive holding the optical core together hasn't gone yellow and brittle and fallen apart from age and heat and UV from the lamp, if the color wheel motor hasn't seized up, if the glue holding the color wheel parts together haven't turned to dust, if the caps on the PC boards haven't all failed, leaked, and corroded traces off the PC boards.

[tschaeikaei]

Ecrabb:
This was written with a smile and should be read like that.
Sorry if you feel offended but please lean back and laugh about it.
That's all it is meant to do.
I wrote that I don't see a point in flame wars. Why then should I start one?
Digital is easier. That doesn't mean all digital users are stupid and lazy.
It means if you are stupid and lazy you could rather use a digital than a crt.
Because crts require effort and technical knowledge. And the
willingness to learn a lot of stuff about the technology.
Regards, Julian

[ecrabb]

[tschaeikaei]

Oh ok. I see you just understood the opposite of what i was trying to say in the first place.
Could be that i should not try to be funny in a foreign language.
Flame wars are like dick comparison to me. There is no point to it.
It's something like "I like pizza" and the other guy saying "spaghetti are better, idiot!"
Where is the point in that?
There is no real comparison of projectors or technologies in those flame wars.
People participating in such things are taking technical aspects as emotional things.
And i do not have the time and interest to participate myself.
What i was trying to say (and that is based on my personal experience about people i bought my projectors from):
These guys switched to digitals. They are happy today that they don't need to call professionals to set the thing up anymore.
And what i thought when i was visiting those people when picking up the projectors was like
"why did you not use the internet, learned how to do it yourself? It is such a fun hobby and so interesting.
These guys missed a lot of fun and payed lots of money to miss it."
That does not mean all digital users are stupid and lazy.
It means those people i got to know were a bit like that.
There is a lot of exaggeration in that post and i thought people would see that and would have fun reading.
But I'm stretching out the topic far to much, this should all be in the off topic section.
So, my apologies about that.
Regards, Julian

[ecrabb]

SC

[GREG1292]

[quote="Curt Palme"][quote="tschaeikaei"]§1 Digitals are to make geometry adjustments easier. That's it :)
§2 After completing the CRTs setup, put the digital into the bookshelf to prevent the books from falling over.
Regards, Julian[/quote]

With the recent flame wars at AVS, I dare you to post that last sentence in one of the CRT vs digital threads. :mrgreen: :thumbsup:[/quote]

No flaming going on anymore took 6 months to show us crt users can take a correct screenshot
and put the digital in it's rightful place holding up books :mrgreen:

[cmjohnson]

To update my last comments, I watched a full movie (Frozen) on my friend's system with the JVC RS40 projector and it was extremely nice.

Then the following evening I watched the same movie on my MP modded 9500LC, which is due for an overhaul, with contaminants in the glycol, and imperfect magnetic alignment, and it was BETTER. Just a more solid, more engaging picture. Nothing that's easy to define, but you see it. The difference is there. I can't tell you exactly why it's better than the digital, with my smaller screen and lower light output, but whatever it is, it gets your attention.