CurtPalme.com Home Theater Forum

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

The purpose of this is spot to move all my blathering out of Dave's thread, so he can proceed with his illuminating exposition, without the annoyance of my gadfly responses. Wink

We can continue to haggle over in this thread, if he likes.

I started out by disputing some of Dave's claims...

> The reason a CRT is not well suited for this is three fold:
1) 4:3 and 16:9 would have to be significantly downscaled to meet the resolving power limitations of the CRT. <

I doubt much 4:3 content would need to be "significantly downscaled". Certainly no "TV" content would. I could argue the real effective impact on 16:9 content, but you've already conceded most of that point, elsewhere. [Besides, let's say you were happy with the resolution, detail, and PQ of 2.37 content at 1920x810p, and thought you had a great picture. So how could 16:9 content scaled down to the same height (1440x810p) not also look exactly as good? Answer: it couldn't (assuming a good scaler, it would be the same). It just might not be quite as good as viewing the full original resolution, at full size. But even then, not as bad as the 3/4 scaling might imply.]

> 2) Uneven tube wear will introduce artifacts in 2.39 content if any amount of 1.85 or 16:9 is watched. <

Admittedly a large problem, UNLESS orbiting is used. Though I'm not sure that wear-banding is best described as "artifacts". At least, I'd never think to include that in a list if I were describing artifacts. It would be significant image degradation though, which is the point you were making.

> 3) People generally want a wide (9’ or greater) CIH screen and on that small of a raster, a CRT lacks the light output for a quality picture. <

I'll grant you that most people do (though some are satisfied with smaller setups, still manageable by CRT), if you change it to "on that small of a raster, a single CRT lacks the light output". [And, BTW, with the way CRT prices have dropped through the floor, the negative cost-factor (though not the complexity) of a dual-CRT blend has been dramatically mitigated, and now compares favorably to a good digi-PJ + anamorphic lens + positioner.]

(Sorry, I couldn't help myself. Smile

Hey, I can be pedantic too! Wink

)

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

> on a Blu Ray disc, a 2.39 movie has less resolution than a 1.85 movie. <

I'll argue this one with you too, if you like. Heck, even if you don't. Smile

Leaving aside old differences from DVDs, where the h-rez was filtered less on 2.35 films than 1.85, because there were 25% fewer pixels to encode. And so the effective detail on scope films could actually be greater (and frequently was), within the bit-budget available. Theoretically at least, that shouldn't be an issue with DVDs in HD formats.

The resolution of a movie in 2.39 on BR is exactly the same as it is on a 1.85 movie. That's because resolution is a ratiometric indicator. E.g., pixels per unit of distance. This is the same on both horizontal and vertical axes, and for 2.39 and 1.85 films.

A 2.39 movie has 25% less pixels in the image, but so what? Granted, a 2.39 film encoded linearly (as they all are, unfortunately) does have less rez than if they were done anamorphically, but that's out of our control (and not what you said).

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

Re: Zooming...

> your scope image will be about half as bright as your 16:9 image <

"Actually Doctor, that's 55.3428%, to be precise. Dammit, Spock! I said about half. I'm a doctor, not some damn computer." Smile

Seriously though, you should mention that some digi-PJs have variable light output settings, that could be used to compensate for this particular deficiency. After all, digitals frequently have lumens to burn (literally). Zoom memories, plus variable output settings could make the simplicity of zooming an easy, attractive, and affordable CIH option for many.

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

The other way that variable light output could be achieved, short of changing the drive current to the bulb, and possibly shifting the color temp, would be to have a motor that could automatically insert a (small and inexpensive) neutral density filter into the image path, internal to the PJ, as needed. (Or, have a variable density wheel, and rotate the proper density filter into place for finer tuning.)

Assuming a high quality image could be achieved on a 1080 panel, using 1920x817 in the zoomed out mode, I'd see this as far better than any of the external lens-based options, since it eliminates a lot of complexity, cost, and secondary lens aberrations. Not to mention the size and weight of these Rube Goldberg contraptions. Smile

It also requires no scaling, and thus no potential for artifacting from that process. It's purely optical.

It also makes more sense than using scaling to perform a vertical stretch, just so that more of the panel could be used. How is electronic stretch supposed to be superior to optical stretch? Plus it preserves the ability to do absolutely ANY AR perfectly in true CIH mode, which was the original objective in the first place. Let's get away from complex, fixed-format, compromise systems (for lotsa bucks), and back to some of the flexibility of CRT PJs.

One final advantage is that mere mortals could actually understand it. Thumbs Up

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

Re: the CONs for Zooming, I'd have to comment...

> 1) no consumer projectors have memory blocks to recall zoom settings. <

Temporary impediment, before the needs were understood. Let me know when you have a real HT projector.

> 2) ...only 75% of the panel’s resolution (the active image area) is used on scope movies, meaning that you have only 75% of the light output <

Easily resolved with dynamic filtering, or even variable apertures, already available and currently being used to achieve high fake contrast ratios.

> 3) You must have treatments above and below your screen to effectively absorb the light of the “black bars”. <

Not a big deal. So does a real theatre. Seriously... 8.5" of black felt above and below your screen, vs. the cost, time, and complexity of strapping a motorized anamorphic lens onto your PJ? And tying things together so they work automatically? No contest.

> 4) Not useful for 720p projectors as too much pixel visibility on scope images. <

Irrelevant. A 720p PJ has only 544 pixel height (and 1280 width) in scope (w/o anamorphic lenses). Not appropriate for a real home theatre. 1080p is getting ubiquitous, and cheap. Why are we even discussing those dinosaurs? Not long ago, even 1440x820 wasn't good enough for you. 1280x544 on a 9' wide screen sucks. Anamorphic 1280x720 isn't much better.

> 5) Not all projectors have the necessary zoom range. <

Not all PJs will find buyers. Look for them in the bargain-bins. The ones that do will meet buyers requirements.

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

BTW, after that last post, I should grant you (before you jump in and pummel me Smile

) that 1280x720 anamorphic, generated by down-converting from 1920x1080 will look a LOT better than stretching 1280x544 up. But still, I've seen digital 1280 content, and even on a little 32" wide LCD panel, there's a big difference in 1920 h-rez vs. 1280 h-rez (sourced natively at 1920; or even 1920 h-rez sourced at 1280). I can only imagine what that would look like blown up 3.4x wider (and 3.4x higher) and beyond. Shocked

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

...further commentary awaiting Dave's moving his comments over in-line...

Tom.W · Joined: 09 Mar 2006 Posts: 6637

OK I'm a CRT guy but did this thread in the digital forum get hijacked ? Uncle Louie is on his way...... Cool

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

I agree with you that 2.35/40 is the same res as 1.78/85 for the exact reasons you explained. But i have found it looks sharper if you do use active area scanning to free up the unused bandwidth in the black above and below the active image, this would have no effective benefit on a digital PJ. This is why i think CIH on a blended CRT is the best way to go. And you dont get that distorted prism image from the slide in lens for CIH on a digital, when they make a digital with a 2.40 display then we can talk.

Athanasios

**AnalogRocks** · Posted: Tue Oct 28, 2008 3:50 am Post subject:

I'd still like to try 3 anamorphic lenses on a CRT Mr. Green

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

**AnalogRocks** · Posted: Tue Oct 28, 2008 4:44 am Post subject:

Tom.W · Joined: 09 Mar 2006 Posts: 6637

The question is where do you find such a lens ? Just name one.

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

Dave asked:
> one question, is this mostly a technical discussion of CIH on CRT and CIH via zooming on digis--like pros and cons and how to resolve. Or a "versus" thread? <

I'd prefer the technical discussion, but feel free to compare the two if you like, since you've got experience with both now. Heck, you had arguably one of the best 8" CRTs there was. If you don't know what a good image looks like, I don't know who does.

> Yes, you could do a 7.5 foot wide scope screen--a 38x90 screen and have a nice bright image. But most don't want that. <

Argg! Perfect aim... an arrow right through the heart. Yeah, I've got a 90" wide screen, and do scope at 38x90. Viewed from 9' back, for a d/w ratio of 1.2, and 45-deg viewing angle. (Though not CIH.) But I wouldn't be bold enough to call it a home theatre, because I've seen the amazing HT's some folks have done. More of an intimate media room.

I'd like to respond to a few other comments, but it'll have to be another day. I've got some other stuff I have to attend to. Thanks for your followups here.

Person99 · Joined: 09 Mar 2006 Posts: 4901 Location: Flower Mound, TX

VideoGrabber · Joined: 09 Apr 2006 Posts: 933 Location: Michigan

> So, you are sitting 2.84x screen height away from the scope image. <

Yep.

> If you have seen my posts, my front row (primary viewing location) is EXACTLY the same ratio <

I knew you were in the neighborhood. Didn't realize it was exactly... probably because I tend to think in terms of screen widths, rather than heights.

> it seems the majority of folks focus on absolute size of the screen instead of viewing ratio--a "bigger is better" mentality <

Absolutely. And if I had built my media room for them, it would have turned out differently. As it is, it works out ideally for 3 adults on a comfortable recliner couch (or just me by myself, sprawled out Wink

). In configuration 2 (it's a convertable room, so the couch is slid back to 11'), it can handle 5 adults (with 2 side seats), and the kids can sit in front on the floor, for a whopping capacity audience of 8 or 9.

> there is a very valid reason for large screens--mulitple rows. <

No doubt about it. Now you're talking HT!

> That would give a second row with your screen size of ratio of 4.42x scope image height. <

In that case, it would have to be be at night, I'd have to open my light-blocking BOC and curtains, and they'd have to be sitting outside on the front deck, peeking in whatever you call a 6' wide living room window. Mr. Green

I never thought of trying that.

> for instance, my screen is just big enough so that my front row is 2.84 and my back row is 4.0x. <

Very interesting. Transmogrifying your 4.0x into d/w generates 1.7x, which happens to be what I'd consider to be my personal farthest "best-quality" viewing distance (=1.85 content at CIA, in room config 2). So you've got a perfect setup.