Agree on stretch being an option, especially if you have to "stretch" to get a Lumis. I have a Panasonic 3000 in one of my setups, and it's fantastically convenient to have one button poor man's cinemascope. I'm really surprised this is not showing up on more higher end units when such an affordable projector as the 3000 can implement this nifty feature. Is it perfect? no but it gets focus pretty close on scope, close enough to not bother with having to refocus and on switching back to native is dead to nuts focused on 16:9.
Sounds like the Lumis has manual shift so wouldn't be possible to have an automated lens memory system anyways. Guess if you can afford one of these Lumins you also can afford an Isco or Schneider, especially now with the newer info that ANSI does not suffer as much as we originally believed when using an anamorphic lens.
Quote:
Originally Posted by owl1 /forum/post/15604622
Guess if you can afford one of these Lumins you also can afford an Isco or Schneider, especially now with the newer info that ANSI does not suffer as much as we originally believed when using an anamporphic lens.
"No, thankfully, it [focus/zoom memories] doesn't offer this facility...The cost of doing this correctly is not inconsiderable and requires a very sophisticated focusing arrangement."
I haven't been following it, but early reports on the Pan 3000, including from Cine4home, said that it worked fine.
Quote:
Originally Posted by owl1 /forum/post/15604622
I'm really surprised this is not showing up on more higher end units when such an affordable projector as the 3000 can implement this nifty feature. Is it perfect? no but it gets focus pretty close on scope, close enough to not bother with having to refocus and on switching back to native is dead to nuts focused on 16:9.
Quote:
Originally Posted by noah katz /forum/post/15604761
"No, thankfully, it [focus/zoom memories] doesn't offer this facility...The cost of doing this correctly is not inconsiderable and requires a very sophisticated focusing arrangement."
I haven't been following it, but early reports on the Pan 3000, including from Cine4home, said that it worked fine.
I previously owned a DPI Highlite and did the "zoom" thing with it. The memories were dead perfect going from 16:9 to 2.35:1. I never had to tweak focus or shift or zoom. This was an expensive projector so I was surprised to see this feature in an affordable unit like the 3000.
"I previously owned a DPI Highlite and did the "zoom" thing with it. The memories were dead perfect going from 16:9 to 2.35:1. I never had to tweak focus or shift or zoom. This was an expensive projector so I was surprised to see this feature in an affordable unit like the 3000."
It needn't be that expensive, stepper motors and encoders are relatively cheap, especially when you're in the realm of $38k.
Sim2 REQUIRES that their projectors be installed by the dealer (or contracted out and supervised by the dealer). This should include some tweaking, but a full calibration is not required by Sim2 which leaves the option of calibration up to the buyer. (In other words, find someone you trust to calibrate.) There is certainly no shortage of qualified folks here on Forum. AVS will calibrate as well.
Quote:
Originally Posted by darinp2 /forum/post/15601281
I'm not convinced of that partially because the CRs that define good and bad ANSI CR and MTF at full resolution are going to be so different. For example, if 100:1 ANSI CR is where somebody says it goes over to being bad, then 2:1 MTF at full resolution is more like where it goes over to being bad. That is, 1% washout effect vs 50% washout effect in order to get to being "bad" in this example. A 100:1 CR during a full resolution MTF test would be incredible, but 100:1 ANSI CR is nothing to be very proud about.
So basically what this says is if everything were ignored (edit: i.e. perfect) but ANSI, the MTF would be over 98% for even a device with 100:1 ANSI.
From what I've read a good 9" CRT can do maybe 30% MTF @ the 1080p limit (rough ballpark estimate). I think JVC has published ~70% on one of their QXGA1 white papers. I have no idea what to expect a quality DLP to deliver but let's say it's 80%. An 80% MTF would mean that the measured contrast between pixels is going to be 10:1 which is much less than ANSI. In other words ANSI becomes a second order effect because it's so much higher than the low contrasts that would yield typical MTF readings of less than 50:1.
Yes. I was thinking of this in terms of that paper earlier. If you go around 3/4ths of the way down in that paper and look at the first graph that says, "Film Dig. Inter. Sys. Data" and has cycles/mm and horizontal pixels at the bottom, the ANSI CR test is very close to where the graph starts on the left, since I'm pretty sure the horizontal pixels value would be 4 and the cycles/mm would be 0.08. The first mark is cycles per mm of 2, so this is so close to the left side of the graph that it would look like it was on the vertical line for zero cycles/mm. And the Lumis would be around .998 there, while 100:1 ANSI CR would be .98 there, like you said. Graphically those would both look like they started pretty close to where the green lines meets the left axis in the graph. The question is partially how much the difference of .998 from .98 on the left edge of that graph tells us about what happens halfway across at close to 2000 horizontal pixels.
Again, you have to keep in mind that MTF is usually normalized to be 1 at the lowest spatial frequency. The MTF of very low spatial frequencies is not all that meaningful because they are all going to be very close to 1. For very low frequencies, the MTF data before normalization is what should be looked at.
Simple descriptions of MTF have been posted before, but I think that it would be useful to do it again. MTF is nothing more than the contrast of detail in the image. It's a curve, starting with the relative contrast of the coarsest detail and going to the contrast of the finest detail that the system can resolve. Why is it relevant to a discussion of the Lumis? It is because it may be the aspect of performance where projectors like the Christie HD6K-M and the Barco DP-1500 have an advantage.
Quote:
Originally Posted by odyssey /forum/post/15611138
Again, you have to keep in mind that MTF is usually normalized to be 1 at the lowest spatial frequency. The MTF of very low spatial frequencies is not all that meaningful because they are all going to be very close to 1. For very low frequencies, the MTF data before normalization is what should be looked at.
Do you consider 100:1 ANSI CR to be poor, good, ...? If not poor, what would you consider poor ANSI CR? If your MTF data for a number of pixels of 4 (the ANSI CR test) is that the 2 white boxes horizontally are each 10 ft-lamberts and the video black boxes are 0.1 ft-lamberts, what does that tell you about MTF at high frequencies? I don't see how this normalization affects the discussion of whether what would be considered poor ANSI CR means that MTF will be poor at all frequencies.
What kind of MTF would you consider poor or good at full resolution (1920 pixels horizontally) or for a 2 pixel by 2 pixel checkerboard pattern?
Quote:
Originally Posted by odyssey /forum/post/15611138
Simple descriptions of MTF have been posted before, but I think that it would be useful to do it again. MTF is nothing more than the contrast of detail in the image. It's a curve, starting with the relative contrast of the coarsest detail and going to the contrast of the finest detail that the system can resolve. Why is it relevant to a discussion of the Lumis? It is because it may be the aspect of performance where projectors like the Christie HD6K-M and the Barco DP-1500 have an advantage.
Nobody is disagreeing that the MTF curve is relevant. The question is whether a point that is at an extremely low frequency (ANSI CR) being at say .98 or .99 tells you that the MTF must be poor at high frequencies. It is not the case with MTF where the room is included, as I mentioned earlier.
I consider projector ANSI CR of 100 very poor. I consider 500 as good and anything over 750 as very good. I think that it's better to leave the room out for this and consider only the projector.
Others will differ, but the threshold of acceptable MTF for me at the highest frequencies is 0.5-0.6. The exception would be at the limiting resolution away from the center, where even 1/4 pixel misconvergence can easily bring it lower. I would want it to be at least 0.5-0.6 at the center. I think that the best DLP designs are close to 0.8 MTF at 1920x1080 at the center of the image.
Again the MTF of the lowest frequencies is 1 or close to 1, by definition, because of the normalization of the lowest frequency MTF to 1. (There are some other MTF formulas that can result in an MTF greater than 1, but I can't remember what they are.) Again, if you take away the normalization factor, the measurement of ANSI CR is almost the same as the MTF measurement of the corresponding spatial frequency using a square wave. My best guess is that 100 ANSI CR would correspond to 0.6-0.7 MTF without normalization, which would be poor performance at that frequency. (edit: I am leaving this last sentence, but it's clearly wrong. The MTF is about 0.99, and although that seems good on a scale of 0-1, it's not at that low a frequency.)
In any case, I don't know what we are arguing about now. I have acknowledged that using ANSI CR as a proxy for MTF performance breaks down at some frequencies if you have confounding factors like misconvergence or anything else that will significantly change the MTF at that frequency but not significantly change ANSI CR. I think that the correlation is still good for most projectors at most frequencies.
Quote:
Originally Posted by odyssey /forum/post/15613792
Again the MTF of the lowest frequencies is 1 or close to 1, by definition, because of the normalization of the lowest frequency MTF to 1. (There are some other MTF formulas that can result in an MTF greater than 1, but I can't remember what they are.) Again, if you take away the normalization factor, the measurement of ANSI CR is almost the same as the MTF measurement of the corresponding spatial frequency using a square wave. My best guess is that 100 ANSI CR would correspond to 0.1-0.2 MTF without normalization.
You lost me there. How would the case like the 10 ftL/0.1 fL (100:1 ANSI CR) correspond to 0.1-0.2 MTF without normalization? I'm not following your math.
Quote:
Originally Posted by odyssey /forum/post/15613792
In any case, I don't know what we are arguing about now.
Quote:
Originally Posted by odyssey /forum/post/15613792
I have acknowledged that using ANSI CR as a proxy for MTF performance breaks down at some frequencies if you have confounding factors like misconvergence or anything else that will significantly change the MTF at that frequency but not significantly change ANSI CR.
I think it can also break down in the other direction with things that significantly change ANSI CR, but do not significantly change MTF at high frequency. For instance, when moving a projector so that its lens shift has it centered on the screen lowers ANSI CR (probably because of reflections going straight back into the light engine instead of at a sharper angle) that likely has little affect on MTF at high frequencies. And as I mentioned, it won't surprise me if that Samsung A800B with just ~130:1 for the center 4 boxes still has good MTF at high frequencies. It depends on what the cause of that lower ANSI CR is. If poor ANSI CR will always correlate well with poor MTF at all frequencies then I should be able to say that this A800B must have poor MTF at all frequencies, but the math doesn't support that if MTF of even .7 is considered good at full resolution. And the logic doesn't support that it must have MTF lower than even .7 at full resolution because of this low ANSI CR issue either, IMO.
Quote:
Originally Posted by odyssey /forum/post/15613792
I think that the correlation is still good for most projectors at most frequencies.
I think it is also pretty good. But that it has break downs in both directions. I think certain reflections inside the projector that take a long path (like lens shift centered, light reflects back into the engine, then some of it makes it back out through the lens, or internal reflections from one side of the image to the other) are not necessarilly going to have enough local effect to lower the MTF at full resolution to where you would consider it poor even if they did lower ANSI CR to where you would consider it poor, based on the numbers you gave.
I have to go with the Isco. The T3 lens offers a longer throw then I planned and I cannot fill my screen without a lens. I have no choice in this case.
Quote:
Originally Posted by darinp2 /forum/post/15614058
You lost me there. How would the case like the 10 ftL/0.1 fL (100:1 ANSI CR) correspond to 0.1-0.2 MTF without normalization? I'm not following your math.
I was thinking 0.1-0.2 at the highest frequency, which is what I would expect from most projectors with 100 ANSI CR and edited my post almost right away. The edited number is still way too low and the bottom line seems to be that MTF at the lowest frequencies is not all that useful, even before normalization for most cases.
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