Front Projector CRT vs. Digital

Discussion in 'Archived Threads 2001-2004' started by Steve Andrews, Mar 3, 2002.

  1. Steve Andrews

    Steve Andrews Auditioning

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    I am sooo close to purchase, yet I am having a hard time deciding between CRT or digital. I know that digital is all the rage, but the bulb life and PQ vs CRT has me concerned.
    So, let's have it - CRT or digital? Can we do this without degrading this thread into bashing and flaming? (I would post this on AVS, but I'm afraid for my life!) [​IMG]
     
  2. Deane Johnson

    Deane Johnson Supporting Actor

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    You need to describe your setting to get a response. Light control is a big factor with CRT, screen size, room size, tolerence for the size of the CRT, budget and so on.

    Deane
     
  3. Micheal

    Micheal Screenwriter

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  4. Guy Kuo

    Guy Kuo Supporting Actor

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    Tough decision, especially for someone who has never had a projector. There are many perfect valid arguments one way vs the other. I doubt there is a "right" answer right now, but I'll throw out some random thoughts that might help you. These are not in any order of importance.

    There are characteristics between digital and CRT which tend to separate them as a class, but it would be misleading to lump all digital projectors into one pile and all CRT's into another. Arguments about the merits of a projector really has to specify what type or even which model of projector is being discussed. That also brings up the problem of variability in setups and familiarity with the particular machine and situation. A ton of mitigating factors means that you're going to be pulled left and right with everyone very much convinced that their take on the "right" choice is the best one that a reasonable person will take. We all have our biases.

    I tend to bias my view of a projection system primarily towards how convincing and transparent the achieved image. This typically means that a system which follows the behavior of very good CRT projection will most frequently fool my eyes into believing that a projected picture is real scene before my eyes rather than just a picture. If you see a truely top notch setup, you really shouldn't be staggered primarily that the image is huge, bright, or colorful. I want the picture to absolutely reach out and give me that convincing illusion that I'm looking through a glass window rather than at a projection screen or better yet that I'm looking through an open window. The screen and projection system should disappear. Things which get in the way of that spoil the illusion.

    What are the things which detract? Visible structure in the image imposed by the projector is one. On CRT projection, those would be visible scan lines in a system which does not have its electron beam focus and video scaling systems well matched. Too few scan lines and you see the picture is made of horizontal lines. Too many and the image begins to blur. With digital projection you have "screen door" effect which appears if the picture elements are too low in "fill." The other way things fall apart with digital is if the pixel resolution is too low for the subtended screen angle. For instance, even with the good fill characteristics of DLP, I see the image begin to break up on an XGA screen when the angle side to side of the screen exceeds about 20 degrees. At 25 degrees, it is still acceptable enough to avoid distracting me, but by the time I reach 30 degrees, I can plainly see that the image is composed of little separate elements even with defocusing. Some people can ignore this problem are more impressed with shear size than avoiding visible pixellation.

    Screen size is a real bugaboo for those just starting with projection. The initial impetus is to have as large a screen as possible. There are very good reasons to choose a more moderate screen size. First, you will maintain better apparent image resolution on a smaller screen which subtends about 30 degrees or a bit less of your viewing angle. Next, you must realize that the amount of light needed to light up a screen increases with the square of the width. It isn't linear. Larger screen advocates have loved the higher light output of digital projectors to illuminate even bigger screens, but one should consider how that is actually affecting your image quality over time and the possibility of tweaking the image. With CRT projection a maximum width of 7 feet for a 7 inch machine, 8 inch for an 8 inch machine, and 9 feet for a 9 inch machine would be reasonable on a nice 1.3 gain screen. Smaller screens mean a CRT will be sharper, brighter, and have longer CRT life. On digital machines, you should think about visibility of pixels and possible light losses should you opt to try some of the newer mods for improving image fidelity. With all machines, it is foolish to opt for a screen which a machine can adequately illuminate when new, but fail to plan for the 50 or 60% drop in light output the machine will undergo over its tube or bulb life.

    Setup. Setup. Setup. CRT owners have long said this mantra and digital projector owners should as well. Bad setup simply ruins the picture. Ambient light on the screen is a very effective way to make an image less dimensional, foggy, and less colorful. We continually hear about people wanting to get into front projection but refusing to control lighting or restrict viewing to night time hours. Gray screens help, but nothing beats keeping all light off the screen for helping your projector achieve its best image. It is a simple basic principle that front projection newbies rail against incorrectly. If bright room lighting while viwing is a goal, then really consider again whether or not you should do front projection. Proper setup of a CRT projector is not a trivial task. A motivated new owner can learn to get maybe 80% of a CRT but it really takes a well experienced pro to get it fully up to snuff. It is here that digital projectors enjoy an advantage, but I'd say that is partly illusory. It is simple to place, aim and focus a digital projector, but that still doesn't guarantee the best image. Your choice of settings, image source, scaler, and application of mods can be just as critical as with CRT projection if you really want the absolute best image from your machine. You simply reach an acceptable plateau more quickly with digital. CRT offers a higher level of performance but it is a lot more effort. One can also push digital up a fair ways with work, but still not quite as far as good CRT.

    That brings up "good" CRT. We are at an interesting juncture at which used CRT's are available at a very good price point. This is fortunate for those willing to undertake the considerable effort needed to get a CRT system into proper operation. I used to believe that any decent CRT system would always outclass digital projection, but no longer can I say that. My modified DLP unit can very adequate beat and probably beat a lot of 7 inch CRT setups. We are at the point which I'd definitely go after 8 inch electromagnetic focused CRT's or better. Those are worth the effort for super good imaging. Below that CRT level, there is good reason to think about digital as a viable alternative. You have to be willing to do some work to bring the machine above factory level performance, but it is possible for some machines. That's not for everyone.

    Everyone - well not everyone is able, willing, or should go to the lengths that super HT enthusiasts take to make their projectors produce a better picture. A lot of use just want to bring a box home, hook it up and enjoy a big picture. That's also a valid approach even if a little sad in my eyes. If you are willing to accept a picture which isn't as nice as on your direct view CRT, but is simply bigger, then a digital projector is a no brainer. It's as close to point and shoot as possible. Just don't expect to get pro class performance and be able to live with it. If you go this route, for heaven's sake, don't go around saying bad things about front projection because you haven't seen anything remotely like what an optimal setup will produce.

    Don't forget the screen. That fabric is the final imaging element and it does make a big difference. This should be budgeted into your system. Stewart makes very good screens and charges more for them. This is one place where more cost does make a visible difference. There are other screen manufacturers and you could even make your own screen, but I would encourage getting an undisputedly excellent screen material if it is within your financial comfort level.

    Processing the video signal can break an image. A good processor won't make a bad projection system look good, but bad processing can make a great system look like mush. If you are doing CRT projection, a line doubler is a minimum for a 7 inch CRT. Any better a CRT and you should get a home theater PC or a good scaler. Otherwise, you will be losing a lot of your projector's imaging ability. With digital projection, you must see how well the internal scaler works. For many, an external scaler or HTPC is once more the secret to feeding the projector something which crisp and free of artifact. So budget in that scaler or HTPC. At the least, plan to add one in the future.

    So CRT or digital? My answer is yes, but please go forth only if you are willing and able to set it up right. Otherwise, you are better off with an RPTV or direct view set.
     
  5. Steve Andrews

    Steve Andrews Auditioning

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    Wow Guy - what a response! I appreciate all the thought, time, and experience you put in your post. This is the type of information I, and others like me (near purchase of first projector) are looking for.

    I have the desire and technical inclination to set the system up correctly - I fit the mold of tinkerer/tweaker that most of us on this forum probably came from. After plunking down the amount necessary to afford a good digital or 8"/9" CRT, you can bet I'll definitely do my homework.

    My concerns with digital have mostly to do with bulb life (continuing cost of ownership seems relatively high). To offset this, the ease of use and portable, small size are great advantages. I suppose my main concern is that since I likely will not have the opportunity to see many of these devices on display before purchase, I'm afraid that I'll be dissapointed in the PQ after purchase (however, point taken - I will most definitely work to acheive the highest quality possible).

    For CRT, the size is a concern, plus the fact that burn-in is a factor. I would be upset to find, should I purchase a used CRT, that I could see the faint presence of the "My Computer" icon from someone's PC in the upper left corner of the display. I've also not seen as many 8" or 9" CRT projectors for sale at the same basic price point as, say, the Hitachi SX5500W (near the top of my list). Perhaps it is because I've focused most of my attention on the digital projectors.

    Again, thanks to everyone who has replied so far - I am relying on your experience to assist me on this, my virginal purchase of a front projection system.

    Regards,

    Steve
     

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