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It's Ruby time!
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Person99



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


PostLink    Posted: Mon May 15, 2006 7:28 pm    Post subject: Reply with quote


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ChrisWiggles wrote:
Darin's conclusions are essentially that 20 or 30K:1 on/off are way lower than what some CRTers are seeing, which may be more on the order of 6-figures, depending on how black the user is choosing to calibrate to.


If calibrated to crush blacks with black as zero light, or correctly calibrating with tse's circuit (which allows zero output blacks), then a CRT's contrast ratio is by definition infinite.

Dave
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ChrisWiggles
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Joined: 12 Mar 2006
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PostLink    Posted: Mon May 15, 2006 8:08 pm    Post subject: Reply with quote

Person99 wrote:
ChrisWiggles wrote:
Darin's conclusions are essentially that 20 or 30K:1 on/off are way lower than what some CRTers are seeing, which may be more on the order of 6-figures, depending on how black the user is choosing to calibrate to.


If calibrated to crush blacks with black as zero light, or correctly calibrating with tse's circuit (which allows zero output blacks), then a CRT's contrast ratio is by definition infinite.

Dave


Yes, but nobody can realistically achieve true blacks without sacrificing some loss of other image attributes which is why most do not errantly set their blacks as blacks as they can possibly go. Most notably there is alwasy the tradeoff between maintaining shadow details and full fade to black, and there are physical limitations imposed that restrict how close you can achieve both of those at the same time, even with gamma tweaks(which do not directly address the physical ANSI limitations, but rather address the effects to a limited but positive degree).

This is the case with any display. Even the Brightside HDR display has limitations, it just so happens that the limitations there are pretty minimal, such that it can exceed the limitations imposed by our eyes.

Our displays, unfortunately do not come close to that kind of performance, but someday they well, which is why Darin spends so much time harping on on/off CR.
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Spanky Ham



Joined: 22 Mar 2006
Posts: 5634
Location: Comedy Central


PostLink    Posted: Tue May 16, 2006 5:00 am    Post subject: Reply with quote

My eyesight is still relatively good at 20/20 in left eye and somewhere between 20 and 40 for the right eye. So, I haven't kept up with any of the advances in eye correction. Every person I have spoken with that has had Lasik is enthusiastic about it though. A friend just went for his two year checkup in Philly and his eyes are still perfect. My cousin is an anesthesiologist and couldn't wait to get to Emory to have hers done. I understand everyones concerns, but I wouldn't hesitate if I needed it. Of course if the inconvenience of glasses or contacts is not that big of a deal, then I would agree with waiting.
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WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Tue May 16, 2006 12:41 pm    Post subject: Reply with quote

Chriss, 10K:1 static on/off CR? I know little/nothing about the H79, but isn't that a DLP unit? Asking if its got a DI is senseless since you're saying static CR. Curious, and confused.
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jokeruh



Joined: 15 May 2006
Posts: 36



PostLink    Posted: Tue May 16, 2006 2:33 pm    Post subject: Reply with quote

Darin modded the H79 with a custom fixed iris. It significantly reduced the light output, but he was able to triple the stock on/off. H79 is a single chip DC3 DLP by Optoma.
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Daniel
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ChrisWiggles
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Joined: 12 Mar 2006
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PostLink    Posted: Tue May 16, 2006 4:03 pm    Post subject: Reply with quote

WanMan wrote:
Chriss, 10K:1 static on/off CR? I know little/nothing about the H79, but isn't that a DLP unit? Asking if its got a DI is senseless since you're saying static CR. Curious, and confused.


yes that's static on/off CR the H79 does not have a dynamic iris. It's a DC3 (I believe) DLP unit.
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jokeruh



Joined: 15 May 2006
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PostLink    Posted: Tue May 16, 2006 4:59 pm    Post subject: Reply with quote

I just saw a thread darin started yesterday in the >3500 forum. it is a detalied explanation of what he did.
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Daniel
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kung fu hustler



Joined: 14 Mar 2006
Posts: 15



PostLink    Posted: Tue May 23, 2006 4:53 am    Post subject: Reply with quote

I just love the audio system,its great.
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BlackSabbath



Joined: 16 Mar 2006
Posts: 219



PostLink    Posted: Sat May 27, 2006 2:00 am    Post subject: Reply with quote

What i would lie to know about the ruby is since its on/off is 15000:1 with the auto iris on, what is it with it off? I have looked on sonys site and other sites that sell the ruby but they only lis the 15000:1 with auto iris on.
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ChrisWiggles
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Joined: 12 Mar 2006
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PostLink    Posted: Sat May 27, 2006 2:48 am    Post subject: Reply with quote

http://www.avsforum.com/avs-vb/showthread.php?t=639051&page=1&pp=30&highlight=ruby+static+onoff+CR

Summary:

about 3K:1 iris open
about 5K:1 iris closed (better than the 004)
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BlackSabbath



Joined: 16 Mar 2006
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PostLink    Posted: Mon May 29, 2006 3:37 am    Post subject: Reply with quote

So basically the real contrast ratio of the lcos pannels is 3000:1.
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BlackSabbath



Joined: 16 Mar 2006
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PostLink    Posted: Mon May 29, 2006 3:40 am    Post subject: Reply with quote

So basically the real contrast ratio of the lcos panels is 3000:1.
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ChrisWiggles
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Joined: 12 Mar 2006
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Location: Seattle


PostLink    Posted: Mon May 29, 2006 4:12 am    Post subject: Reply with quote

BlackSabbath wrote:
So basically the real contrast ratio of the lcos panels is 3000:1.


...no, they're getting 5k:1 with the iris closed down. That's a static CR number. I don't know how much of the inherent panel CR that is. I don't know what they spec the panel at, so I don't know how much more than 5K:1 might be possible theoretically.
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BlackSabbath



Joined: 16 Mar 2006
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PostLink    Posted: Thu Jun 01, 2006 11:54 pm    Post subject: Reply with quote

Yes but with it open its 3k:1 so what I am saying is without the iris its 3k:1 which would mean that the 5k:1 is not the panels themselves merely the iris adding to the panel's 3k:1. The reason I ask is because without very very high contrast ratios the only way to get good shadow detail is to crank the brightness which kills blacks.
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ChrisWiggles
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Joined: 12 Mar 2006
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Location: Seattle


PostLink    Posted: Thu Jun 01, 2006 11:59 pm    Post subject: Reply with quote

BlackSabbath wrote:
Yes but with it open its 3k:1 so what I am saying is without the iris its 3k:1 which would mean that the 5k:1 is not the panels themselves merely the iris adding to the panel's 3k:1. The reason I ask is because without very very high contrast ratios the only way to get good shadow detail is to crank the brightness which kills blacks.


No, you misunderstand the function of an iris. In both of these positions the iris is fixed, so those are static on/off CR measurements with no iris movement at all. So yes, the panels are natively getting at least 5K:1 with the iris closed down, because the iris here is fixed and is thus a passive design (in essence) in the optical path. This will be dimmer than having the iris open, but allows for a greater contrast ratio. If the panels were limited to 3K:1, it wouldn't matter how far you closed a static iris, you wouldn't get more than that.

Obviously, a dynamic iris allows you to move beyond the static CR limits of the system, but obviously with some limitations. That's the 15K:1 number.
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BlackSabbath



Joined: 16 Mar 2006
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PostLink    Posted: Fri Jun 02, 2006 4:44 am    Post subject: Reply with quote

I did not misunderstand, what I wanted to know is what is the contrast of those panels if the iris were not there, clearly it is 3k:1. Yes the 5k:1 is static however it is dependent on the iris, with no iris at all just the raw panels is what I was refering to.
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ChrisWiggles
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Joined: 12 Mar 2006
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Location: Seattle


PostLink    Posted: Fri Jun 02, 2006 5:08 am    Post subject: Reply with quote

BlackSabbath wrote:
I did not misunderstand, what I wanted to know is what is the contrast of those panels if the iris were not there, clearly it is 3k:1. Yes the 5k:1 is static however it is dependent on the iris, with no iris at all just the raw panels is what I was refering to.


No, but I think you are confusing the presence of an iris with static panel contrast. There is always an iris present, it's just the position (how open or closed) the iris(es) is(are) that may be able to better maintain the full panel contrast capability.

If the panels were only 3k:1, you would never see (regardless of how closed the iris were) a CR greater than that. An iris is just an iris. I think you're confusing an iris into something that its not. A fixed iris can't increase the CR beyond the capabilities of the panels. At best, it can help maximize the CR of the panels that is inherent. Obviously this may require up to multiple irises closed down pretty tight to control the light path and limit stray light and things like that (I'm not so intimately familiar with this) which cut down light output a great deal. This is why a lot of projectors have adjustable irises so you can choose how closed down you want to go to increase the static CR.
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BlackSabbath



Joined: 16 Mar 2006
Posts: 219



PostLink    Posted: Fri Jun 02, 2006 5:38 pm    Post subject: Reply with quote

So the 3k:1 with the iris open is not the real contrast of the panel, the contrast is being lowered by stray light bouncing around inside the optics then? Similar to how an LC crt has better contrast than an AC one because it stops the stray light from reflecting off of the tube face, correct?
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WanMan



Joined: 19 Mar 2006
Posts: 10261



PostLink    Posted: Fri Jun 02, 2006 5:59 pm    Post subject: Reply with quote

Black, you need to look at a diagram for an LCoS light engine. The potential for light scattering comes well before then lens assy. Let me see if I can find such a diagram.
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ChrisWiggles
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Joined: 12 Mar 2006
Posts: 2529
Location: Seattle


PostLink    Posted: Tue Jun 06, 2006 12:18 am    Post subject: Reply with quote

BlackSabbath wrote:
So the 3k:1 with the iris open is not the real contrast of the panel, the contrast is being lowered by stray light bouncing around inside the optics then? Similar to how an LC crt has better contrast than an AC one because it stops the stray light from reflecting off of the tube face, correct?


No, it's not like AC/LC, that improves ANSI contrast ratio in a CRT.

Remember that the iris "open" doesn't mean that there is no iris, it is just at a position that is more open relative to the "closed" position. Just like having the iris "closed" doesn't mean that the iris actually is closed all the way (no light at all). Those are just relative terms for the two positions. I'm sure you could probably design a light engine with an iris position even more open, or just a worse light engine altogether that would have much lower on/off CR capability. Part of what makes adjustable iris features (distinct from dynamic irises) so attractive is the ability to move between high on/off CR modes for critical viewing (such as film in a darkened room) and an opened up iris for brighter viewing for say the superbowl or sports where you may want to have lights on in the room so you can find your guacamole.

It's more like you'll see many DLP displays with varying on/off CR with different kinds of iris features, all with HD2+ chips in there. The chips all have the same (essentially) CR capability, but depending on the light engine design, you can capture some amount of that capability. Just because you slap a chip that may be able to hit say 10K:1 or something on/off CR doesn't mean that every display is going to be able to take full advantage of that. Indeed, as you'll see, most of them will be getting a few thousand to one on/off CR, or maybe a bit higher if they have iris features that close down the iris at the cost of light output. A lot of people value light output a lot more than on/off CR numbers, so that's a sales decision in the design. The numbers Darin gets with his H79 are probably not something that average viewers might appreciate because the display is then so dim, yet it gets very high on/off CR numbers.
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