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I don't necessarily agree with the opinions expressed here. The thing is, most of the reason you cannot achieve good black level on your CRT, IMO, is that you run it too hard. You run it too hard because you have too much ambient light level often. The only way you can get rid of the ambient light level is to get your room darker. So its a cycle, either up or down.


In my opnion, you should get your room as dark as possible, and run your CRT no higher than it absolutely should be. This will give you better blacks and longer life on your CRT and better resolution because you are getting a smaller spot size.


Most theaters don't make their walls black probably more due to aesthetic reasons than anything else. I believe that it is absolutely true that it would provide a better image if they did.


Others may disagree, but that's how I feel about it. My Dwin, which is not the most high end CRT in the world and not the best at holding black, does quite well on black level against a background that is (though not black itself) very dark during viewing. Since I control the light level pretty well (at night when I'm doing critical viewing) I can run the projector low enough to get good black level when properly calibrated. And I've found that it increases practical resolution as well. I used to think that 650 lines was about all the Dwin could do on a 16:9 screen, but that was partly due to contrast being higher than it needed to be. Now I'm getting 720 and might be able to squeeze a bit more, because I've got the contrast down, something I could only do by getting the room darker, not lighter.



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Dean Roddey

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I think Dan Houck makes a good point. I have no objection to grey blacks if it doesn't impair my home theater experience. In fact, I got into this HT stuff to avoid the multiplexes, where the image is never in focus and subtitles do the jitterbug for two hours.


Last night I saw "Gladiator" on a CRT (HTPC/DVD) that easily beats what I see at theaters -- black level, detail, color saturation, audio, everything.


In my second attempt to start a flame war this evening, I'd like to state that the standard for black levels demanded by many in this forum has transcended that of the theater experience!
 

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If the ceiling, floor, and side walls were black, the front wall wouldn't need to be (because there would be essentially no source of reflections), so you could have a gray border around the screen.


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Noah
 

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Yes and more power to them. My point was not that they are going too far, it was that you don't have to go that far to have an eminently satisfying HT experience.


Believe me, I'd love to have that $100K Sony/Faroudja setup in my house. But I don't have to have it to be very happy with the HT experience. In the last two years, it has become quite possible to have an excellent front projection setup for less than $10K, all the video elements (projector, screen, scaler, DVD) included. And that ROCKS!


I might add that this group has a heckuva lot to do with that fact. All of you deserve a huge thanks from people like me who never would have made it to this level without the resources of this group. THANK YOU!!


Dan
 

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OK, Lurker #25, why is OK to want a better-than-multiplex focus and image stability, but not OK to want better-than-multiplex black level?


Personally, I want a better image than my eyes can see and better sound than my ears can hear. And I want to pay as little as possible to get there.


You gotta problem with that? http://www.avsforum.com/ubb/wink.gif


-yogaman

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Reality is so restrictive...
 

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Once you eliiminate the ambient light in your room - any properly functioning and properly adjusted CRT projector can easily produce what the eyes will see as being true black (the absence of light) on your screen. Both within the image raster and outside of it. That is a given and any suggestion to the contrary would just be laughable to the scores and scores of us who read these forums and who do this with our CRT projectors day in and day out.

There are no bars. There is no halo. Black in a starscape is black. And stars and shadows in a starscape are still rich with detail.


In practice, projected film does not produce black to this degree. Some light passes through the darkened areas of the film frame. Even still, black is still pleasing to the eyes (granted maybe not to those who advocate "film sucks" in AVS threads). A CRT projector is also capable of simulating what black looks like in a projected film image if that is desired. Very easily. This is also a given.


Debate till the cows come home just about everything else.

Be it light output, resolution, sharpness, color, focus, convenience, etc. But the ability of a CRT projector to make black is pretty much a given.


Bob


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~ The Sultan of Cheap ~


[This message has been edited by RobertWood (edited 08-16-2001).]
 

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You're absolutely right, Bob. That's why the G90/Faroudja combo has never been bested in anything I've seen. These days, CRT is also pretty reasonable. Only it wouldn't work in my room because of ambient light and 14' cathedral ceiling that wife said "no toucha".


But if I were building a dedicated theater in a basement where I could hang that puppy from a ceiling, that would be it. I know people that have that setup and it doesn't require a lot of maintenance. Once you become experienced at convergence, it's a snap.


The beauty of digital projectors is they are so versatile in application and enable folks like me to have an HT where it would otherwise be pretty much impossible. And I think at some point they will achieve CRT levels of black. But not this year.


Dan
 

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Quote:
The beauty of digital projectors is they are so versatile in application and enable folks like me to have an HT where it would otherwise be pretty much impossible.
Absolutely! You'll get no argument from me there, Dan.

That is precisely why I'm about to shift to using them full time. While I didn't find it impossible, believe me my 4 year marriage to CRT projectors has been a rocky one. Divorce is imminent. http://www.avsforum.com/ubb/smile.gif


Bob



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Try this little experiment if you have laptop computer. Play a movie on your HT projection screen and at the same time place your laptop on your lap positioned so its screen. Now open a few windows on the laptop so it emits some bright light towards your eyes. (You DID calibrate your laptop to produce D65 first didn't you! Mine is) Anyways, notice how the contrast and blacks look on your projection screen. Next close the laptop and look at your projection screen again. Notice anything different between having the laptop creating a bright surround (open) vs a dark surround (closed)?




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Guy Kuo
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Ovation Software, the Home of AVIA DVD


 

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Does this make sense?


My dedicated theater has black fabric bordering the screen and covering the complete front wall. This fabric is obviously blacker than the blacks from my 10HT, not to mention blacker than most if not all CRT's. When watching a movie the black fabric continually reminds me that my projector won't even get close to true black. Hears the question!!


Would using dark gray fabric instead of black fabric as a border on the front wall fool my eyes into thinking that my projector is projecting darker blacks than it really is? Would it at least stop reminding me that my blacks are not true black?


My guess is that it would help improve the perceived black level. It is sort of like how very dark blue suits or dark gray suits sometimes look black untill you compare it to a black suit side by side.


What is your opinion or actuall experience?

Thanks -William
 

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Yes, yes, opinion. It should definitely help though. Your eyes are easily fooled.
 

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This thread is perfectly titled! I beleive as well that using a dark gray fabric that more closely matched the blank level of your projector will help. This is unorthodox, but it will help your perception, which is what really counts.
 

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Agree, the black wall is a bad idea. You just need enough absorbent black around your screen to absorb any light spill. Movie houses don't do the walls black, neither should you.


Another thing that will help develop a realistic attitude about black level is this. Go to your local movie house and watch a movie with a critical eye towards black level. Guess what? It's not a whole lot blacker than your 10HT and pretty similar to my Boxlight 38T (Sanyo XP21N clone).


I think it is really laudable that the leading edge folks on this forum have achieved black levels which significantly exceed that which can be experienced in a movie theater. My benchmark for this is the G-90/Faroudja combo that Faroudja exhibited at CES. That picture went far beyond anything I've ever seen in a movie house. And for only a mere $100 grand! http://www.avsforum.com/ubb/smile.gif


However, my criteria is "movie theater-like" and on that basis, I don't see the need or desirabilty to greatly exceed that standard. My whole thrust is to have an image that equals or exceeds that available in a decent movie house. I am firmly convinced I can reach that goal with the Boxlight/Grayhawk/Quadscan/?DVD player setup I'm putting together now. Heck, my wife and I thought we were 90 percent of the way there just shining the Boxlight on a painted wall and inputting from an old Toshiba 2109.


Apply the reasonable tweaks you can find here, don't get too caught up in technology and ENJOY THE SHOW! http://www.avsforum.com/ubb/biggrin.gif


Dan

 

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do you have any ambient light here?

i have black velvet bordering my screen for an LT150.

while i think the blacks are very good, they of course aren't as deep as the velvet.

i also don't think it matters since the masking is used only to create a live window where the movie exists. It is there to divorce the perception of the room/wall from the movie, not to give you a black scale to judge the picture against. Black is only a matter of concern within this live area and is relative all times within the picture.

a darker gray in a lights off setting would still appear black i would think.


have you tried the pink/red filter or Munsil tweaks for the VW10HT?

i think you would have more sucsess with something like that.
 

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I think discussions about perceived black level and ways to induce blacker blacks are interesting and potentially useful for getting the most out of our home theater setups. However, one point that has not been mentioned here is that the sensitivity of our eyes to very low light levels is not fixed: it changes over time. In the perception literature this is commonly referred to as "dark adaptation." We now know that for the first half hour you are in a darkened room your eyes become increasingly able to respond to low light levels. So if you look closely, the perceived blacks right after you turn out the lights in your theater should be blacker than what you see 30 minutes later. Usually we don't notice this shift because it happens very gradually over the approximately 30 minute period.


One consequence of this is that a demo of a projector that you see five minutes after leaving a bright room will be misleading.
 

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I have my 10HT firing directly onto a matte white wall. The room itself is perfectly dark before watching a movie. Whilst watching a movie, the sharp borders of the lcd panels are a good enough border themselves as the matte white wall behind is always darker than even the a pitch black scene from the FP. Because the eyes have to adjust and focus at extreme relative levels, (eg: our eyes need to resolve the man's black suit against the desert sun) I think that the relative contrast ratio of an image is responsible for the "WOW" factor more than the absolute black level factor. Yes, I do have contrast set to 90-95%, and yes, the absolute black levels from this projector are atrocious, but given the above, I have watched "Mission to Mars" several times and have been engrossed in the movie to the point that I forget to check how bad the black levels are. This is the perception factor at work and it's very real. Anyway, isn't this what HT is all about? Actually trying to watch a movie and enjot it?


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Even though I have spent many years studying visual perception and am very critical about image quality, I never have trouble forgetting all the shortcomings of my hometheater and just enjoying the movie.


My attitude is that you should do what you can, within reason :), to make the video presentation as good as possible. Once you have done all you could, just get over the fact that it is not perfect...it never will be...and enjoy the movie.


Once you accept that nothing short of a stage performance, that includes film, is a *perfect* visual presentation of reality it is easier to get over the fact thagt your particular home theater is not perfect.
 

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As you may notice, this is my first post to this forum, but I have had a SONY10HT for a year and a half now and may be able to offer some useful suggestions.


First, Furnishing the room with a darker ceiling, drapes, and paint does improve the contrast ratio, especially in those scenes that have both bright and dark regions of the image. In these scenes your eye can use the brighter spot(s) as a reference and hence perceive the darker part of the image as black. It's those low contrast dark scenes that are the killer for the stock 10HT. This is a matter of black level, and not just contrast.


I am doing a couple of things you might find useful. While my ceiling, side and back walls are dark, my front wall, behind the screen is a comparatively light gray. I have been using bias lights on both sides of my 16:9 screen and I think they help the perceived black level. The key to bias lights is that they should produce a diffuse neutral (gray) light and be positioned so that no light from them reaches the screen, just your eyes. So executed, they don't hurt the measured contrast ratio, but do help the perceived black levels by providing a brighter reference point in your field of view. They also make viewing feel more comfortable relative to a completely darkened room. I think they are a must.


The other thing you should be aware of is that it is certainly possible to significantly improve the contrast ratio and black levels of a 10HT, both by careful measurement based tweaking, and more recently by use of Color Collection or CC filters. As you may know, the bulb on the10HT produces more green and blue than red. As a consequence, it is necessary use relatively low "gain" settings for green and blue in the various color temperatures, in order to have those colors stay balance with the weaker red. Unfortunately, by keeping the green (and blue) gain low, you lose contrast in the one color, green, that the eye is most sensitive to when it perceives the intensity or luminescence of the image.


By using Color Correcting filters to filter out some of the green and blue, it is possible to drive the green and blue LCD panels much harder thus improving contrast ratios and the black level as well. If you are interested in more details, I have documented this stuff on my web-site at http://home.pacbell.net/steve367


I also agree that at some point you should sit back and enjoy the image. But you should also be aware that there are some fairly simple things you can do to improve that image if you so desire.


Steve



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Steve Smallcombe
 
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