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Discussion Starter · #1 ·
As the opinions flow in regarding the next step in DLP, the new HD DMD from TI, the "dark" chip, I am starting to think that projected black is the best we will ever get from digital projectors. When I say that, I mean that what should be black will always be a slight luminousity.

To be honest, this is something I have learned to accept. My current projector, the Sharp xv-s55u has quite a poor blacklevel. On most material, it performs very well. Bright, colourfull, etc..etc..however...come the Sci-fi movies, and my heart sinks a bit.

When I am supposed to see the Alien in the corner, watch Ripley form a distance..I see grey. The "darkness" of space is bright enough to light up my room.

Now, I will ask everyone who has the opportunity to test new projectors to do this test...what I, and others, like to call the "shadow test". Have the projector on with no signal, or something that is supposed to be black. Then, put your hand infront and describe how much of a shadow your hand is able to cast on the screen.

With my projector..it is like there is a spotlight on my hand http://www.avsforum.com/ubb/smile.gif


I saw the Seleco HT200, and did the shadow test...and, well, I was rather disappointed.

I have accepted this one, and dare I saw, only defeat of digital projectors at the hands of CRT projector. In most other aspects, we have them beat.

I saw a demo of an NEC CRT a week ago with no signal. The lights were out, and it was nearly pitch black in the room. The screen had no illumination on it whatsoever. I ask the guy, u gonna turn the projector on? He said it already was. Now, that my friends, is black level. And for those of use who do not desire CRT's, this is something we wil never have.


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David Mendicino
 

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Well...yes we can.


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Jeff

Currently - Zenith 7" CRT, 80x60 1.3 gain screen


Soon to be - 107x60 1.3 gain...with whatever higher rez DLP gets its act together (finally)with Panamorph or B stock/etc 9" CRT
 

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As for now, yes.


As for tomorrow, no.


No technology lasts forever. It is always superceded,


For example,


propeller---> Jet engine

Dolby Pro Logic---> DTS/Dolby Digital

Porsche air cooled engine---->new Porsche water cooled



CRT is King of the Hill now.


However, its days are numbered.


Jeff


 

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Never is a long time. http://www.avsforum.com/ubb/smile.gif


1100:1 contrast ratio was "unachievable" a short time ago but now is available in the Sharp DLP and others.


Much of the light that is in the blacks appears to be scatter from the dimples on the mirrors when in the off position. (the dimple, for lack of a better term, is the place on the front where the post connects on the back) It seems to me that if these dimples could be filled, much more of the scatter would be controllable. Anyone have a putty knife? http://www.avsforum.com/ubb/wink.gif


Did anyone else notice that the SAME 1280x720 (dark) DMD used in the RPTVs from Hitachi, Panasonic and Mitsubishi is used in the Sharp projector but generates 2x the contrast? Does Sharp know something those other companies don't?


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Huck
 

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There's one problem. CRT has true black only when it's displaying full-screen black signal. With any non-black area, some energy (electrons) will leak and phosphors will glow at spots not intended.


DLP mirror surfaces can't be perfectly flat. Slots in between the mirrors can't be perfectly black.


I'm guessing that GLV with laser may be able to achieve almost infinite contrast ratio even under checkerboard pattern since lasers can be controlled for no leaks. Unfortunately, they may not allow this kind of laser device to be used in home environment.
 

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Having read so many recent threads on black levels I wonder if Digital Projector aspirants should still be worried about just this. I mean the very knowledgable discussions on the subject proved that black level is kinda 'relative' and can be improved by eliminating or reducing light scatter, reflections and point of references for black.


For those who haven't seen a CRT PJ in action, you need to, at least once, so you realise the problem is not JUST Black level.. it's so many other areas.. the image is .. for the lack of a better word..smooth and deep. Granted it's smaller though.. get a good small picture or blow a crappier one.. pick your poison.


I've seen good digital PJ screenshots and good CRT PJ screenshots and although screenshots are no reflection (no pun intended) of the what the eyes sees on the screen, they still let you know how 'bad' a picture can get.. and trust me.. with CRT it doesn't get too bad http://www.avsforum.com/ubb/wink.gif


I'm like everyone else.. waiting for Digital PJ's to improve so I can ALSO have a larger screen.


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Buyer's Guide to HTPC for Newbiess>c>
 

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While CRT blacks are an admirable goal, the black level of film is more reasonable a goal for digital projectors.


I think that many of the current digital projectors are getting pretty close to the contrast and black level of film today.


Everything is improving as the digital projectors continue to evolve with technological advances.


-Dean.
 

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i heard from the ti folks at cedia that the HD2 chip which is in test now has substantial contrast and black level improvements. digital is improving at a massive rate. i think never is a long time.


greg


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Compaq MP2800 DLP, 1Ghz htpc w radeon aiw, 45 x 80" diy accoustically transparent screen, lexicon dc-1. ipaq touchscreen for control
 

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I just wanted to point out that there are 2 seperate issues. There's absolute black level (i.e. the shadow test), and there are shadow details (can you make out what's going on in that dark scene). The two in my mind are independent. I don't really care at all about the absolute black level (but then again I've never seen a CRT, I'm sure others have a very different opinion), but shadow detail is *very* important. Shadow detail is all about gamma. How much light should the projector emit for 7.5 IRE, 10 IRE, 15 IRE, etc.? Most digital projectors are shipped with really stupid values, and hence look terrible in dark scenes. Even after tweaking contrast and brightness, I think in general (depending on the projector) you will still end up with very sub-optimal results...


I just think that we need to distinguish between shadow details (or contrast in dark scenes) vs. absolute black level (i.e. project an all black screen, and compare). I'm sure CRTs always win on absolute black level, where as shadow detail I think is a different question.


Mike



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Discussion Starter · #11 ·
That is a good point, regarding absolute black and shadow details. I am concerned about absolute black, which I am sure when you have a nice low level adds to the picture in a way that we cannot comprehend, and maybe why CRT looks so good in sometimes undescribable ways.


Once you get absolute black, shadow detail can be adjusted as you want, because you won't have any limitations.


Oh, the TAW DILA looks very interesting..especially with all these black hole theories about it's light source http://www.avsforum.com/ubb/smile.gif

My guess...cold fusion..hehehe


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David Mendicino
 

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I would like to second Dean's statement. Sometimes we get caught up in perfection and lose track of the ultimate goal, which in my case is enjoyment of movies and sports. I have a Panasonic DVD connected to a CrystalImage and an RCA DTC 100 feeding my Richard Martin calibrated DILA/ISCO. I find that source material varies so much that I can hardly blame my equipment. With a high quality DVD or especially good HDTV movie, my eyes cannot tell the difference from what I would see at the local movie house. There is another thread that discusses "Black level on DVDs" http://www.avsforum.com/ubb/Forum10/HTML/008764.html


So until the sources get better my digital projector is up to the task. By the time we have HDTV DVDs I am sure there will be a new technology that beats CRTs, DLPs and LCOS. So

instead of debating which technology will win find a good transfer DVD that has a story and enjoy the movie.


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Jim Nissen
 

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Dean makes an excellent point about the target being the

black level of film.


If you are primarily interested in movies - which as of

now are shot on film - then the black level of film is

what you have to live with anyway.


For film transfers, the fact that a CRT can go to a blacker

black than film is really "guilding a lilly" - the CRT

won't be asked to project true black, but "film black".


Greg
 

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well, guys, i guess i am at the opposite end of the scale, as i always owned CRT projectors for home use and just once, briefly, saw a LCD projector displaying a picture.

i hardly ever go to the movies (call me cheap, but at almost $10 per ticket i rather wait for the DVD release!),and,last time i went to a movie theatre was to see ID-4 back in 1996 and i couldn't believe my eyes...the picture was very much "washed-out", the "blacks" just weren't there, it was more like a dark grey.i remember asking myself: what happened to the "blacks"???...

at least to the eyes of someone that had been used to watching videos on CRT's for many years.

having said that, i also have to point out that quite often, when watching movies on my CRT projector, i have to turn up the contrast/brightness controls way up to get an acceptable shadow detail, and that sometimes leads to "blooming" of the picture...it is almost like a double-edge sword...!

i can't wait now to go see one of the new crop of DLP projectors using the 1280x720 chip and put on a movie like "DARK CITY" to see what the picture looks like, as that is a movie that has always given me trouble with my CRT on shadow details.it also has,to my eyes, too much overall "absolute black" in the picture and,truth be told, i find that same "problem" with too many other DVD's,laserdiscs and cable broadcasts as well...so, perhaps the "problem" lies with the CRT technology, plain and simple!...there is such a thing as too much "absolute black", just as there is the opposite.

all i know is that my next projector will be a digital unit, as i find that CRT's have reached their peak performance based on a technology that is basically 50 years old !
 

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"i heard from the ti folks at cedia that the HD2 chip which is in test now has substantial contrast and black level improvements"


Were any numbers mentioned?


Thanks


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Noah
 

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I think shadow detail is important too. if I go to a movie theater and watch a space flick, the image is definitely not pure black but more like an almost black. There is still some light coming out of the projector through the film. In dark scenes, looking directly at a film itself, the black areas are not fully opaque. The thing is, i can see what's going on in the dark scenes. It is the ability to see what's going on that is just as important. If the black level is dark enuff to give you the impression it is black, then that is enuff for me, as long as i can see what's going on.
 

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About CRT black, as I was saying, it's not absolute black unless the gun is not shooting out any electrons. If you display a checkerboard pattern, some energy will excite the phosphors at spots that shouldn't be glowing at all. Now that amount of glow is VERY small, but I just want to point out that we need to be careful with the word "absolute black."


If I'm wrong, please point it out to me.


GLV can, under the laws of physics, produce absolute black even under varying patterns. Of course, some light bouncing off the objects in the room will cause some glow in the dark areas. Now that I think about it, one needs to paint the entire room black AND must wear a black bodysuit with just the eyes shown. Of course, the eyes glow a little. Hmmmm..... We have to see the image to appreciate it.....


I'm sorry. I think I'm trying to be funny.
 

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I haven't had a chance to really take a shot at a good digital unit yet. I am sure I could make one sing.


I will add further, that I fully believe that digital projection units will eventually fully supplant and exceed CRT units in all ways that you could possibly desire, and in many ways tht you have yet to dream of. This is the way it has always been, and will continue to be.


It will just take time. If you want it to happen today, or over the next two years, and at a reasonable, reachable price for YOU...

TOO BADs>


It ain't gonna happen.


Science marches on, but not THAT fast.


Twenty years from now, you can read the words that, " It took ten years for the promise of digital projection to fully bloom", or something similar. It will take three seconds to read the words, thus one forgets, in the mists of time, that TEN YEARS had to pass. This is the way it has always been.


People have a tendacy to hear and see and believe what is easy and convienient and personally desireable, not what the truth is.


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Ken Hotte

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[This message has been edited by KBK (edited 09-13-2001).]
 

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It all boils down to contrast. The human eye has a threshold limit. The CRT can be at or above that limit. There is no reason to think that LCD or DLP can not also achieve such contrast. Currently it is a balancing act. If you want brightness you must illuminate the LCD with larger angles of light. This degrades the contrast. But it is not a fundamental technological hurdle. Laser based LCOS systems have demonstrated such contrast. With time you will see contrast beyond the human detection limit. Then we should all be scared. Because then your sense of reality can be messed with.
 
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