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post #361 of 2011 Old 06-13-2017, 09:47 PM
 
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It seems pretty obvious that wobulation, by virtue of it happening prior to the light going through the lens, requires the lens to be able to resolve 4K in order for the wobulation itself to double the number of resolvable pixels once it goes all the way out the other side. That just seems like common sense to me. If you just trace a path through one pixel's position then another with a slight offset angle, through the lens, then clearly that new angle will form a completely new light path which, if the lens isn't good enough quality, will simply blur it all together in aggregate and result in no additional detail.

Of course things are way more complicated than that in practice, given that light is both particles and waves, so you have to look at diffraction as well as ray casts (even in a theoretical treatment of an imperfect lens -- which they all are). Lens aberrations would have to be smaller than the wavelength of light in order for there to be no appreciable diffraction effect. What's funny is that just a few weeks ago a paper was published regarding microfacet theory in computer graphics, which touches on this. Basically, for the most part graphics treats light like rays and ignores wave properties, but at certain scales that actually does make a difference in the final result.
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post #362 of 2011 Old 06-13-2017, 10:36 PM
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Quote:
Originally Posted by RLBURNSIDE View Post
It seems pretty obvious that wobulation, by virtue of it happening prior to the light going through the lens, requires the lens to be able to resolve 4K in order for the wobulation itself to double the number of resolvable pixels once it goes all the way out the other side. That just seems like common sense to me.
It seems like common sense to me too, but I've seen enough smart people assume otherwise that it must not be common.

The whole point of these eShift technologies is to show smaller detail than is possible just with the native chip and no shift. And showing finer detail at the same MTF requires a better lens. It doesn't matter whether you paint 1 pixel at a time, 1/2 the pixels at a time, or all the pixels at the same time. Real world lenses require the same quality in all those cases as far as contamination outside of where the photons were supposed to go.

Was my E3 example clear enough? If you sit a person at say 10' from the display, put up the E, then use the worst lens where the viewer can still tell that all that is being displayed is an E, that same lens will also work for the 3, but if the E and 3 are displayed so quickly in succession that it looks like one image, the user will not be able to see that the image is an E3 instead of a blocky 8. Resolving the E3 requires a better lens than the image of the E required and a better lens than image of the 3 required. The lens quality required for the person to see the E3 is the same whether they are shown at the same time or shown in super fast succession. Do you agree with that?

Thanks,
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post #363 of 2011 Old 06-14-2017, 01:06 AM
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Perhaps thinking about a square millimeter on the lens would help. No matter if native or wobulated, a certain number of created pixels must pass through that area, therefore that area must be able to resolve the desired number of pixels produced even if they aren't created simultaneously.
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post #364 of 2011 Old 06-14-2017, 04:50 AM
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Originally Posted by TheronB View Post
Perhaps thinking about a square millimeter on the lens would help. No matter if native or wobulated, a certain number of created pixels must pass through that area, therefore that area must be able to resolve the desired number of pixels produced even if they aren't created simultaneously.
The thing is there aren't more "created" pixels going through the lens at any one time, and the pixels that go through are the same size. All that's happening is they are going through twice as fast in slightly different parts of the lens. Lenses are generally most sharp in the center and get less sharp towards the edges, so the half pixel alignment difference of images of same pixel density shouldn't require a more resolving lens. At most it might require more advanced lens coatings because of the increased light "turbulence" with the pixel shifting, but that's about it.

Also, the "created" pixels are created by your brain, not the lens.

Finally, let's not forget the only native 4k dmd is 1.38" and now *this* would require a much more expensive lens than an xpr 4k projector due to its size. This is why Ti is so focused on using the 0.67" DMD as lens cost for their native 4k DMD would be too costly for consumer projectors.

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post #365 of 2011 Old 06-14-2017, 05:03 AM
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But they are going through at different spots, so the lens must be able to resolve those areas properly.

Using your logic, the result would blur together similar to the single line grid pattern. It's just a gray mess.

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post #366 of 2011 Old 06-14-2017, 05:16 AM
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But they are going through at different spots, so the lens must be able to resolve those areas properly.
A lens is not digital, it is analog. It is most resolving at the center and will gradually be least resolving at the edges.

Since you are talking about a half a pixel shift, the "different spots" will be extremely close in proximity and thus will make no difference since a lens is analog. If a lens was digital and had a pixel grid it would matter, but since it is analog it will make no difference. If the lens can fully resolve pixels near the edge with 2716x1528 being projected, then it should have no problem resolving the same image shifted slightly a moment later - as lenses have no persistence, are fully analog, and light moves FAST.

The only thing you might need is a bit better lens coatings to potentially tame reflections because of the more rapidly shifting light, and you would need a lens that fully resolves 2716x1528 as opposed to one that mostly resolves it. Sometimes pj manufacturers use lenses that have significant aberrations to save money, and if you were to do this with xpr it would defeat the purpose as the artifacts would spoil it when your brain does the processing.

But again this is a high quality lens capable of fully resolving 2716x1528 we are talking about, not native 4k. In fact if this theory of needing a more resolving lens were true then XPR projectors would need a lens that is significantly *higher* resolving than native 4k (xpr virtual res is 5432x3056) which is bunk IMO.
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post #367 of 2011 Old 06-14-2017, 05:30 AM
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Originally Posted by Ruined View Post
But again this is a high quality lens capable of fully resolving 2716x1528 we are talking about, not native 4k.

Got it, the lens resolution capacity doesn't need to comply with 4K, as our eyes provide the rest - in a manner of speaking. Thanks for clarifying that.
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post #368 of 2011 Old 06-14-2017, 05:37 AM
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Got it, the lens resolution capacity doesn't need to comply with 4K, as our eyes provide the rest - in a manner of speaking. Thanks for clarifying that.
Right, your eyes/brain assemble the two ~3k images to make 4k, not the lens. Just like your eyes/brain assemble the dlp sequential RGB color to make a full color picture, not the lens.
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post #369 of 2011 Old 06-14-2017, 05:43 AM
 
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OMG what did I start???

I am seeing a lot of people state what they believe as fact and truth but I haven't seen any scientific lens research links or references, test results, engineering studies, etc. to prove or disprove one or the other's stance. Who has these here and wants to share them?

So far I'm still leaning towards ruined's stance on this because a lens' resolving power is across its entire surface (with the small differences as you go towards the edges as he states) and is indeed analog, but I am also very intrigued by what Darinp2 is posting and want to learn the science behind it and would love to see more of the actual science behind it and what he is saying rather than crude graphics of Es and 3s. As of now his explanations aren't hitting home or lighting the bulb in my Lyme riddled brain!

Meanwhile, I am reading everything and the follow on responses with much intensity and anticipation!

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post #370 of 2011 Old 06-14-2017, 06:13 AM
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I'm eager to learn whether the constant extra DLP workloads for our brain prevent Alzheimer.

First our brain had to assemble the RGB segments to one coherent image, next we got 3D (assembling two images) and now our brains have to asemble two 3K images to one 4K image...
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post #371 of 2011 Old 06-14-2017, 06:15 AM
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Originally Posted by Frank714 View Post
I'm eager to learn whether the constant extra DLP workloads for our brain prevent Alzheimer.


First our brain had to assemble the RGB segments to one coherent image, next we got 3D (assembling two images) and now our brains have to asemble two 3K images to one 4K image...
Lol. DLP: the thinking man's projector.
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post #372 of 2011 Old 06-14-2017, 06:52 AM
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Look at the pixel shift explanations on DPReview and other photography sites. Pixel shifting technology requires a higher quality lens.

Our eyes will always be sampling the image just like a camera sensor, and wherever the higher resolution comes from, it requires better lenses to show off its advantage.
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post #373 of 2011 Old 06-14-2017, 09:01 AM
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I'm just waiting for reviews of the UDH60/65 to come out. It doesn't matter how high quality of a lens pixel shifting requires or if these projectors count as native 4K or not as long as the image they output is good for the price.
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post #374 of 2011 Old 06-14-2017, 09:03 AM
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Quote:
Originally Posted by Frank714 View Post
Got it, the lens resolution capacity doesn't need to comply with 4K, as our eyes provide the rest - in a manner of speaking. Thanks for clarifying that.
Except that what Ruined has been posting about all that matters is what goes through the lens at an instant in time is flat out BS. Funny how he seems to like to have things both ways. He seems to have gone from the 1/2 pixel offset between sub-frames not requiring any better lens, to maybe you want a better lens due to the 2 sub-frames.

I thought my E3 example was pretty clear. It doesn't require any persistence in the lens at all, just persistence of human vision. Do you think that if a lens was just good enough to show the E by itself and just good enough to show the 3 by itself, that this would mean it could show the E next to the 3 at say 120Hz and have it look like E3 to the viewer (not a blocky 8)?

This subject can get complicated, but people should get past this mistaken notion that all that matters for the quality of static lens required is what passes through them at an instant, and not the composite frame being built.

--Darin
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post #375 of 2011 Old 06-14-2017, 09:13 AM
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Originally Posted by Ruined View Post
The only thing you might need is a bit better lens coatings to potentially tame reflections because of the more rapidly shifting light
Looks like you are just making stuff up as you go along. This theory of your's is nonsense. What does "more rapidly shifting light" have to do with anything? Do you think that changing the effective colorwheel speed on a single chip DLP changes the lens quality required?
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and you would need a lens that fully resolves 2716x1528 as opposed to one that mostly resolves it.
You've been telling us the whole time that eShifting doesn't require any better lens because all that matters is what goes through the lens at one instant and now you are claiming that you need a better resolving lens. So which is it? Do you need a better resolving lens to help resolve the sub-pixels created by the half pixel shifted sub-frames or not?

--Darin
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post #376 of 2011 Old 06-14-2017, 09:15 AM
 
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Time division multiplexing can't make the lens better. And there's no free lunch in physics right? If the modulator + XPR chip is on one side of the lens, and the screen on the other, then the lens itself is the limiting factor by which XPR's benefits are visible or not. So in other words, since XPR brings the imager from 2.7K to effectively UHD (more or less), then the lens would need to resolve 4K to take full advantage of XPR, logically.

That said, when I walk up to the wall on my w1070 DLP, I can see sub-pixel structure and the gaps between pixels, and those gaps are smaller than pixels in a UHD grid, so I don't believe that having an OMG awesome (=expensive) lens is all that necessary to derive a substantial benefit from XPR or Faux-K or even true UHD / 4K.

I see the quality and size of the lens vs imager to determine how sharp the image is from edge to edge, which is definitely NOT perfect on the w1070 although that's likely also because my mounting job isn't perfectly aligned. Which brings up another point: if you want a perfect edge to edge focus, you need perfect alignment, there is no way around that. That's where I see most problems coming from. Even if I got a pro mounting done at my place, it wouldn't stay perfectly aligned because I live next to a busy street and when trucks roll by my projector rattles a bit each time. So I have to refocus once in a while. (although I'm sure there's also alignment drift happening too).

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post #377 of 2011 Old 06-14-2017, 09:27 AM
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OMG what did I start???

I am seeing a lot of people state what they believe as fact and truth but I haven't seen any scientific lens research links or references, test results, engineering studies, etc. to prove or disprove one or the other's stance. Who has these here and wants to share them?
Dave,

Sorry that I don't have links for you, but I think we can work out this question about whether what matters for projectors lens quality requirements is the whole composite frame your eye's see or just what a super high frame camera would see coming off your screen.

I'll go back to my example of 3 different images.







Ruined is so far off the rails that he thought this example required persistence within the lens. It only requires persistence within human vision, which is a fact.

I'll start without the persistence though. Please imagine these 3 images being displayed slowly one at a time through a lens that obscures them. Do you agree that the 3rd image requires a better lens for a human viewer to see that there is a 1/4 square spot that is brighter than the rest than the lens quality required for a person to see that there is a square on in the first and second pictures?

Thanks,
Darin
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post #378 of 2011 Old 06-14-2017, 09:51 AM
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Originally Posted by RLBURNSIDE View Post
Time division multiplexing can't make the lens better. And there's no free lunch in physics right? If the modulator + XPR chip is on one side of the lens, and the screen on the other, then the lens itself is the limiting factor by which XPR's benefits are visible or not. So in other words, since XPR brings the imager from 2.7K to effectively UHD (more or less), then the lens would need to resolve 4K to take full advantage of XPR, logically.

That said, when I walk up to the wall on my w1070 DLP, I can see sub-pixel structure and the gaps between pixels, and those gaps are smaller than pixels in a UHD grid, so I don't believe that having an OMG awesome (=expensive) lens is all that necessary to derive a substantial benefit from XPR or Faux-K or even true UHD / 4K.

I see the quality and size of the lens vs imager to determine how sharp the image is from edge to edge, which is definitely NOT perfect on the w1070 although that's likely also because my mounting job isn't perfectly aligned. Which brings up another point: if you want a perfect edge to edge focus, you need perfect alignment, there is no way around that. That's where I see most problems coming from. Even if I got a pro mounting done at my place, it wouldn't stay perfectly aligned because I live next to a busy street and when trucks roll by my projector rattles a bit each time. So I have to refocus once in a while. (although I'm sure there's also alignment drift happening too).
4K is 8.3mp and I've read most decent dSLR lenses can reach 40mp in the sweet spot with shifting technologies, so although the lenses are obviously designed differently, I'd assume the lenses would not need to be outrageously expensive considering the chip size. When we approach the 33.2mp of 8K, we may be looking at a substantial cost difference.
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post #379 of 2011 Old 06-14-2017, 10:27 AM
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Darin, I am not changing my argument, you are changing yours. You stated the lens requirements are built upon the resolution of the "final composite image;" in that case you are arguing the lens needs to fully resolve 5432x3456 (18.8M pixels) as that is the final composite resolution of the 0.67" XPR DMD as discussed in the XPR whitepapers. 18.8M pixels. Really?? We are not in JVC eShift land anymore where the final composite resolution is a mere fraction of that.

I stated it needed to fully resolve 2716x1528 (4.2M pixels), as the final 4k UHD resolution is created by your eye/brain and not the lens, and thus the composite resolution is irrelevant. Now you appear to be walking back your original statement to "a higher quality lens" instead of a lens that fully resolves 5432x3456 as you originally stated.

If the lens fully resolves 2716x1528 that is all you need. If the lens is poor quality (poor sharpness at corners of frame, aberrations, etc) then it is not fully resolving 2716x1528.
You don't need a lens to resolve 5432x3456 and 18.8M pixels in this case as was your original argument. You just need the native resolution fully resolved; your eye/brain takes care of the rest.

And yes, better lens coatings contribute to reducing of light artifacts and hence better resolving the native resolution. When you are utilizing different surface areas of the lens elements due to shift, hence hitting that surface area at additional angles with more light (lens elements are not flat) better coatings can help control internal reflections and thus allow you to better resolve the desired resolution.

Given the DMD, shift mechanism, & lens all have no image persistence properties and given the speed of light it is physically impossible to be projecting more than 4.2M pixels through the lens at any given time. And, given a lens is fully analog and has no pixel grid, whether the image is in one place or shifted half a pixel it makes zero difference as long as the lens can fully resolve 2716x1528 across the lens surface being projected upon in the first place. That's all there is to it, all of the image compositing, combining, etc occurs post-lens. The 4k UHD is assembled by your eye/brain, not the lens.
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post #380 of 2011 Old 06-14-2017, 12:47 PM
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I am almost wishing we were back on the video game conversation lol. This thread has been a ride. Going back to placing blame on ProjectorCentral for their terrible preliminary assessment! In all seriousness, I was told the UHD60 ships next week. I sent a list of questions to Optoma I have however their engineers or techs are @ InfoComm so I may not hear back until next week I was told.
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post #381 of 2011 Old 06-14-2017, 01:03 PM
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post #382 of 2011 Old 06-14-2017, 01:16 PM
 
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Nice. By next year I could see 4K lasers being 3K easily. Let's see what Epson and others can bring to the table in terms of affordable 4K + laser. Competition is great. (for us).
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post #383 of 2011 Old 06-14-2017, 01:17 PM
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Originally Posted by rkabir View Post
I'm just waiting for reviews of the UDH60/65 to come out. It doesn't matter how high quality of a lens pixel shifting requires or if these projectors count as native 4K or not as long as the image they output is good for the price.
It is a $2500 projector....paid almost twice that for the Epson LCD 1080P 3100 projector....I'm keeping perspective and seeing what trade offs I am willing to have to get me by 2 years and save 70% of my money.

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post #384 of 2011 Old 06-14-2017, 01:18 PM
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I am not sure it's been discussed but the manufacturer is saying that the lack of 3D is a limitation of the DLP Chip.
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post #385 of 2011 Old 06-14-2017, 01:20 PM
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Quote:
Originally Posted by Ruined View Post
Darin, I am not changing my argument ...
It sure looked like you changed it between:
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In this case, if you had two dlp projectors, one 2716x1528 0. 67" without XPR and one 2716x1528 0.67" with XPR, I don't believe you would need a more spec'd lens ...
and
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... and you would need a lens that fully resolves 2716x1528 as opposed to one that mostly resolves it.
Do you need a better lens for 2716x1528 0.67" non-XPR than 2716x1528 0.67" with XPR or not?

I already told you that "fully" is a relative term with resolving. Every lens blurs the image and it is a matter of picking a threshold for how much blurring is allowed before a lens is said to not fully resolve the detail.
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You stated the lens requirements are built upon the resolution of the "final composite image;" in that case you are arguing the lens needs to fully resolve 5432x3456 (18.8M pixels) as that is the final composite resolution of the 0.67" XPR DMD as discussed in the XPR whitepapers. 18.8M pixels.
No, I was simplifying things for people and the bottlenecks in the projectors (such as the sub-pixels not really being independent or not enough bandwidth to make the finest detail independent) matter too. As far as the lens requirements with real lenses we are discussing, whether the final composite image goes through the lens at the same time, at 2 different times, or painted one tiny area at a time doesn't matter.

This can get into some complicated stuff, but you seem to have trouble with even some stuff I consider pretty simple. I think you should learn to walk before you try to run and so I'll go back to something I consider pretty simple and see if you can figure it out.

I'll leave your ridiculous argument that shifting the image 0.02% requires a better lens as that is so far into the noise that it is ridiculous to include it when you can't even understand factors that dwarf that.

I'll put my example in my next post so people don't have to wade through the above.

--Darin

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post #386 of 2011 Old 06-14-2017, 01:23 PM
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For those trying to understand lens requirements with eShift models, here is a thought experiment.

Let's say there are 3 projectors that are each required to display one of the images. Projector A needs to display the E in image A, projector B needs to display the 3 in image B, and projector C needs to display the E3 in image C.



Do any of the projectors A, B, or C require a better lens in order to display those required images to humans and have the humans be able to properly make out what the image is displaying?

People can think of it like an eye chart at a doctors office if they want to. People with 20/20 vision are supposed to be able to respond "E" to the image from the first projector, "3" to the image from the second projector, and "E3" to the image from the third projector.

People can also think of it in reverse if they want. Think of those 3 images as eye chart values on a piece of paper at the doctor's office. Does the third image require better vision to make out properly than the first 2 images?

--Darin
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post #387 of 2011 Old 06-14-2017, 01:30 PM
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Regarding lenses needed to fully resolve 4K...this is measured in line pairs per millimeter and it corresponds to the actual size of the micromirrors. Each micromirror measures 5.4 microns, so each pair of alternating lines spans 10.8 microns. This is equivalent to 93 line pairs per millimeter in order for the image on the screen to include all the available resolution from the DMD. A lens of this quality would not be possible to include in the subject projector at its price. Hence a softish picture when compared next to a projector with a lens capable of passing 93 lp/mm. In the absence of comparison, however, one might be perfectly happy. Ignorance is bliss.
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post #388 of 2011 Old 06-14-2017, 01:36 PM
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Originally Posted by Pete View Post
Regarding lenses needed to fully resolve 4K...this is measured in line pairs per millimeter and it corresponds to the actual size of the micromirrors.
Once you start overlapping the images from the micromirrors such that human vision integrates them into one then it isn't just the actual size of the micromirrors, but finer detail that the projector is designed to try to convey to those humans with those 1/2 mirror offset images. Just like with eShift on JVC projectors. When you turn eShift on it isn't just the size of pixels on the 1080p chips that matter. 1080p+eShift projectors are basically designed to be able to convey information that overall is between real 2K and real 4k. The lens is part of conveying that finer detail.

For example, for just the following image the lens requirements are essentially the same whether the image is created with just 1 micromirror, 2 micromirrors, or 7 micromirrors.



Despite some ignorance around here, whether the 2 eShift images go through the lens at the same time or at different times, as long as the human vision system integrates them into one, it basically makes no difference for lenses of the type we are discussing.

--Darin

Last edited by darinp; 06-14-2017 at 01:41 PM.
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post #389 of 2011 Old 06-14-2017, 01:43 PM
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Originally Posted by RLBURNSIDE View Post
Nice. By next year I could see 4K lasers being 3K easily. Let's see what Epson and others can bring to the table in terms of affordable 4K + laser. Competition is great. (for us).
I sure hope so! $5K is still too rich for my blood right now... but 2.5-3k is starting to be more reasonable for a laser based native 4K HDR projector.
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post #390 of 2011 Old 06-14-2017, 01:48 PM
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Originally Posted by TheBrandon View Post
I am not sure it's been discussed but the manufacturer is saying that the lack of 3D is a limitation of the DLP Chip.
Where did you read that? Curious as DPI uses same DMD in E-Vision 4k laser and it supports 3d.
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