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post #1 of 49 Old 12-30-2015, 07:24 PM - Thread Starter
 
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JVC Projector Dynamic Iris Function Writeup

PDF attached.Some of you may be aware I am finishing up a writeup on testing I did between the JVC X500, X70, X550 and X750 including contrast measurements, black level comparisons, and a comparison of the 4 projectors. In doing this testing, I became intimately familiar with the function of the dynamic iris and how it translates onto your screen. I felt that the information on the DI deserved its own thread since it is a wealth of information in itself and the DI behavior is not as obvious as one would think. I also investigated the dual iris system. I have attached a PDF white paper so to speak that hopefully many of you will find informative and open a discussion. Let me know what you think! I will also be posting this in my shootout thread. This is also attached as a PDF.

JVC Dynamic Iris Function Technical Writeup


I will attempt to explain the fuction of the Dynamic Iris on all JVC Projectors that feature it. The beginning sections are basic understanding of the iris system and the latter portions are more indepth and might be new information to some. I also conducted tests on the upper end models and their dual iris.

The X3/X7/X9 and X30/X70/X90 model years did not include a dynamic iris. The black level is set and fixed wherever you have the aperture setting. By lowering the aperture setting and closing the iris more, you are getting a darker picture, but gaining contrast and achieving a lower black level. In other words you are sacrificing brightness for increased contrast and better blacks.

The Dynamic Iris we will be discussing gives JVC projectors the ability to maintain peak brightess while increasing contrast and black level during dark scenes which is where we want to have the best black levels.

There are two menu settings for the iris:
-Mode: Manual/Auto1/Auto2
-Aperture: 0 to -15

When manual mode is used, the aperture is fixed (static) wherever you have it set. A setting of 0 results in the brightest picture, but the worst contrast, and the worst black level. A setting of -15 clamps the iris down decreasing brightness, increasing contrast, and providing deeper blacks.
Here is a graphic showing the iris at various settings:



Notice several things here. The “Max” aperture setting can not actually be set by the user. The iris will only clamp down this far when using Auto1 or Auto2 (A1 and A2). In Manual mode, you can select anywhere from 0 (fully open) to -15 (fully closed). Rather, I should say that -15 is the fully closed position when using Manual Iris mode. In A1 or A2 mode, assuming you set the aperture to zero, the range of the iris during use is from 0 to max.
Now, this is where things get confusing.

Lets assume you have the following settings:
Mode: Auto1 or Auto2
Iris Position:
0
And lets assume these are your contrast ratios at each aperture position:



In this configuration, the range of your iris is from 0 to Max Closed. But this begs the question, when does the iris actually activate? And when it does, how far does it close? Well, its actually not too complicated…

-----When does the aperture close to the “Max Position”?

When in Auto1 or Auto2, regardless of where you have the numerical aperture set to (0 to -15), the iris will always close to the MAX position when displaying a fully black scene or image. I should note this is not exactly true, if there is some non-black content, such as a mouse pointer (if you are using a PC) or one small word of text that covers less than 2% of the screen, this will also activate the Max aperture. I use Vudu streaming service, and Vudu has a screensaver which is simply a black background with a small “VUDU” logo about 100x50 pixels and with this screensaver, the max aperture does engage with this screensaver. Anything more than this, and the max aperture will not engage…

Examples of scenes that will NOT engage the max aperture mode:
-Scenes in space (most scenes in Gravity for example)
-Very dark scenes such as Harry Potter Voldemorts army on the hill
-Interstellar when they leave the wormhole (very dark space scene)
-Space scene in Stars Wars 5, just after the yellow text flows by

That being said, my initial thoughts were…well…if I’m only getting 500,000:1 contrast during full black scenes, this is kind of a joke isn’t it? Well, not really. What I came to realize is that many movies have extended fade to black scenes, transitions, or scenes in total dark and the aperture makes a huge difference here. The reason (I am assuming) that the Max aperture does not engage at any level above this is because the bright parts of the scene would simply be too dim because the iris cuts down nearly all of the light. Next question then is…


---When the Dynamic Iris is engaged, but not displaying a fully black image or movie scene, how does it function?

There is another aperture position that is not in the graphic above that we have not touched on yet. We will call it for now “-17”. We all know that the DI does engage during those Interstellar and Star Wars scenes but we know the iris does not fully clamp down to the MAX position. During these dark scenes, the iris clamps down to a position just a tad past -15 to our fictitious -17 position. Essentially, during dark scenes that are not quite dark enough to activate the Max position, the iris will close just a tad past -15. Heres what I mean by that….

We measured the black level on a JVC X500 at a Manual aperture setting of -15 to be about 0.8 Lux, and then we measured the black level with the aperture in Auto mode to be about 0.75lux during non-total black scenes like Interstellar or Star Wars which is slightly darker than the -15 maual setting. In fact, regardless of where you have the numerical aperture setting, when using A1 or A2, those dark scenes will always close to that -17 position (again, unless the scene is total black). Doesn’t matter if you have it set to 0 on A1 or -15 on A1, the wormhole scene in Interstellar will always have a black level of 0.75 lux.

Essentially, your best black level during movie content that is not fully black is going to be equal to or very close to using a manual setting at -15.
Now, we begin to see the advantage of the Dynamic Iris versus a projector without a DI. Lets assume we have a DLA-X500 with a DI and an X500 without a DI (just bare with me) and we need to get at least 12foot-lamberts onto our gigantic screen. Lets assume the projector without the DI needs to have the aperture set to zero to get those 12fL and our black level is going to suffer at a measurement of 3 lux as previously stated. With the X500 that has the DI, we can leave the aperture at zero, retaining our 12fL during bright scenes and set it to AUTO so that for our dark scenes, we aren’t stuck with a 3lux black level. The pj with the DI will clamp down to -17 during dark scenes and to MAX during fade to blacks.

This is main advantage of the DI in my opinion…good blacks AND still being able to fill a big screen with enough light…Without a DI you would need to choose between getting enough light or having good blacks…
But there is more…


----The difference between A1 and A2 Mode

Auto1 and Auto2 do not differ in the mechanical function of the iris at all. They function exactly the same in that regard. Where they differ is in the way they “treat” the image.
When using Auto1, the projector modifies the image slightly, focused on creating a more contrasty image…It takes the dark parts of the image and makes them even darker and the bright parts even brighter by boosting them. In my opinion, this results in many of the dark areas being too dark and you lose much detail. To some, the image may appear darker but this is just image treatment.

Auto2 focuses on gradation and preserves the image more naturally applying very little image treatment and maintains more of the original image.
As I delved more into the Auto modes, I eventually noticed something wonky was happening…When leaving the aperture at -15 and setting it to A1 or A2, we noticed that the images were not being treated the way we had seen before. We switched from -15 to -6 and suddenly the image was being treated more. We went from -6 to zero and the image was being treated even more.
What we discovered was, based on where you have the numerical setting, also depends on how much the image is artificially treated.

Image Treatment




Last but not least…given all of the above information, we can determine the following. On the left are examples of some possible aperture and iris settings and to the right are the black levels and possible aperture positions. For example, When set to Auto and -8, the Aperture can fluctuate from -8 to Max, the peak lumens are 1,000 and the max contrast is 500,000:1. The examples below are assuming your projector has a native CR of 50,000:1, a dynamic CR of 500,000:1, and a peak lumen output of 1,300lumens. These contrast, black level, and lumen numbers are fairly reflective of the measured output of the DLA-X500



Key and Notes:
Black Image BL – The black level – in lux – of a totally black scene or image as described above
Dark Scene BL – The black level – in lux – of a dark scene that is not a total fade to black. See above for description.
Peak Lumens – This is the peak output of the projector in lumens.



-----X700/X900 and X750/X950 Function – Dual Iris

Things go even further because the X7** and X9** models feature a DUAL Iris system whereas the X500 and X550 models feature a single Iris.
In the dual aperture projectors, there is a front iris and a back iris, both of which are adjustable.

When you set the iris to MANUAL, and you start moving the slider from 0 towards -15, you are manually adjusting both irises. Now, I do not claim to be an expert on the dual iris system as the rear iris or the light engine iris is not visible without taking the projector apart, but it seems like with every click, the front iris closes one click and with every 2 clicks the rear iris moves. When set to Auto 1 or Auto 2, the rear iris stays fixed wherever you have the numerical setting but the front iris still functions dynamically as described already in this paper.

The effect of this is that when using the Auto1 or Auto2 settings, the best dynamic contrast ratios are actually achieved with the aperture set to 0. When using A1 or A2 and setting the iris to -15, you actually have a slightly worse dynamic CR. However, native contrast (MANUAL mode) is still best with a -15 setting. In other words, your best dynamic CR is achieved in Auto mode with the aperture at zero. Your best native CR is with the aperture on Manual at a setting of -15 but this results in reduced light output.
Please look at my other threads, mainly the X500 vs X70 vs X550 vs X750 shootout thread, to see an example of this where I have listed the measured contrast ratios for each projector, noteably the dynamic CR’s for the X750 which is the only one on that list with a dual iris.
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Last edited by Mozen; 12-31-2015 at 03:30 PM.
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post #2 of 49 Old 12-30-2015, 07:25 PM - Thread Starter
 
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post #3 of 49 Old 12-31-2015, 02:31 AM
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Great write-up, solidifies all the observations over the years and brings in a few interesting details. Good work.

One thing you could add though regarding the advantages of the iris is that beyond providing more brightness, opening the manual iris up also raises the ANSI contrast ratio. So while the native on/off contrast (sequential contrast ratio, the one measured with a full white and a full black field pattern) goes down, the ANSI contrast (simultaneous or intraframe contrast ratio, the one measured with the ANSI checkerboard patterns) goes up, and quite significantly.

The DI therefore allows to get both more ANSI contrast on bright pictures with a mid to high APL (as the manual iris is open wider) and more on/off contrast on low APL pictures (as the dynamic iris closes down), which when used around -8 or -10 gives (manual iris setting with Auto 2 enabled) provides a very nice picture overall (provided it's neither too bright or too dim for that set-up). Opening the iris further usually causes more DI artifacts on difficult scenes as the native on/off contrast decreases further, so comes with more trade-offs. But overall a manual iris setting of -10 to -8 (roughly) provides a great overall picture, with more ANSI contrast, a great dynamic contrast with few DI artefacts thanks to the native on/off being still decent.

This is another thing you might want to add in your report, which is that while the fully open iris is provides the best dynamic on/off, it's also the setting with the most DI artefacts (which is different from the picture treatment difference between Auto1 and Auto2 you mention).

For this reason, I was actually looking forward to being able to open the iris on my X500 (I started at -15 to get 60cd/m2 and I'm now at -10 to get 55cd/m2) instead of dreading it. I get better ANSI contrast and with the DI the same black levels. Good compromise, especially in Auto2 where there is very little picture treatment.

ANSI contrast is more time-consuming to measure and also more difficult, as both the room and the operator clothing can influence results. If you want to give it a try, I suggest using the Greg Rogers modified method (using only measurements at the four squares in the centre of the ANSI contrast checkerboard pattern) and reading up about how to do it properly. It's not as straightforward as on/off contrast, which isn't influenced by the room at all.
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post #4 of 49 Old 12-31-2015, 03:20 AM
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Fantastic write up. I see your explanation of dual iris's is very beneficial for 3D blu ray movies which were post-produced with abnormally low exposure. With the 6710, I had to crank down the gamma to 1.8 to get the brightest (mid-tones) picture (0 aperture setting, Auto 2) with 3D movies. With my RS600, it's nice to know the max contrast with solid deep blacks is realized with auto mode 2 and 0 aperture setting. I have a list of abnormally dark exposure 3D blu rays and I'll definitely check this out with. Thx for all the hard work putting this paper together. Truly amazing write up.
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Quote:
Originally Posted by Manni01 View Post
Great write-up, solidifies all the observations over the years and brings in a few interesting details. Good work.

One thing you could add though regarding the advantages of the iris is that beyond providing more brightness, opening the manual iris up also raises the ANSI contrast ratio. So while the native on/off contrast (sequential contrast ratio, the one measured with a full white and a full black field pattern) goes down, the ANSI contrast (simultaneous or intraframe contrast ratio, the one measured with the ANSI checkerboard patterns) goes up, and quite significantly.

The DI therefore allows to get both more ANSI contrast on bright pictures with a mid to high APL (as the manual iris is open wider) and more on/off contrast on low APL pictures (as the dynamic iris closes down), which when used around -8 or -10 gives (manual iris setting with Auto 2 enabled) provides a very nice picture overall (provided it's neither too bright or too dim for that set-up). Opening the iris further usually causes more DI artifacts on difficult scenes as the native on/off contrast decreases further, so comes with more trade-offs. But overall a manual iris setting of -10 to -8 (roughly) provides a great overall picture, with more ANSI contrast, a great dynamic contrast with few DI artefacts thanks to the native on/off being still decent.

This is another thing you might want to add in your report, which is that while the fully open iris is provides the best dynamic on/off, it's also the setting with the most DI artefacts (which is different from the picture treatment difference between Auto1 and Auto2 you mention).

For this reason, I was actually looking forward to being able to open the iris on my X500 (I started at -15 to get 60cd/m2 and I'm now at -10 to get 55cd/m2) instead of dreading it. I get better ANSI contrast and with the DI the same black levels. Good compromise, especially in Auto2 where there is very little picture treatment.

ANSI contrast is more time-consuming to measure and also more difficult, as both the room and the operator clothing can influence results. If you want to give it a try, I suggest using the Greg Rogers modified method (using only measurements at the four squares in the centre of the ANSI contrast checkerboard pattern) and reading up about how to do it properly. It's not as straightforward as on/off contrast, which isn't influenced by the room at all.
Hey Manni - I will add that stuff to the report for sure, thanks for your input. I also am interested in measuring ANSI contrast since I have the equipment to do it with accuracy so hopefully I can get around to that soon. I too use a setting of around -6 to -8 on my X500 for the same reasos you mention. At -10 I simply dont have the brightness. I like to have around 13 to 15fl for 2D viewing
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Excellent work Mozen! I'm among many here
who I'm sure really appreciate this write up.

There is only one thing puzzling to me, since I
own the new RS600 which replaced my RS57:

Your description of the (new) DI is how I hoes it would
work, but yet it doesn't really seem to. Your description
matches how the DI in my RS57 worked: i could
have the manual iris set as high as I wanted for
bright scenes, and for most dark scenes the DI
would close down making it look like the black
levels I'd get with a closed manual setting. So
a "best of both worlds" as your description seems
to depict.

But with the RS600, if I set the manual iris to a brighter
setting, say - 6, without the DI I get raised black
levels. And even putting the DI on doesn't seem
to change this much - most, almost all, dark scenes
display those elevated black levels. Only full
fade to blacks seem to engage the DI at all, or
very rare super low APL shots. So the "best of both
worlds" benefit I got from the RS57 no longer
occurs with the RS600 (which has been probably
my main disappointment hhis far).

The only clue is perhaps in your report: that there
is little manipulation of the image with lower aperture
settings, and of course with the RS600 my aperture
Is set lower than it normally was with the RS57.

Still, your report suggests that nonetheless the DI
should be shutting down to about -15 for
dark scenes no matter where I set the aperture,
and if that where the case I shouldnt have these
complaints since, when I set the iris anywhere from
-13 to -15 and leave the DI off the black levels
look beautiful.

So...I remain confused.
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post #7 of 49 Old 12-31-2015, 04:15 PM
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(Sorry for bad formatting above. Since I'm away
on vacation it was typed
on my iPhone. I have to say that spending any
remotely lengthy time typing on any mobile
device, iPad or iPhone, is so torturous compared
to the desktop experience that I can not believe
the world is supposedly making this transition
to mobile computing. How in the world can
people take it?)
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post #8 of 49 Old 12-31-2015, 08:48 PM
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Formatting or not Rich I tend to agree with your observations on these models. As you know we both had the 57 and I too felt like although most on the old thread kept advocating for more clamping, I felt in my particular setup (running in a non, but close bat cave), with an AT screen at mid-back throw, I needed those extra lumens so my iris was more in the -3 to -5 range. Even so I never felt like my black levels suffered when using Auto2 (matter of fact my FTBs were the best I'd ever seen in my theater!).

This year even when running at between -8 to -10 I keep feeling (and don't get me wrong as you'd have to pry this machine out of my cold dead hands at this point!), like my FTB is just not as good. Maybe the aggresive reduction in the code logic is by design (as we suspect), because I'm sure in one way shape or form JVC were hearing the negative overtones in the previous threads (oh yeah… they spy on them for sure!), on how bad the pumping was on end credits and heavy inter-scene mixing of black&whites, and JVC decided to back it off and let the native contrast do it's thing because they were already beating their competition without it (but maybe TOO much this year me thinks!) .

This year when I check out these scenes I see none of that (blowouts/clipping), but as you say I too questioned at times if it was really even working or stuck like others (but later confirmed the DI is moving as expected).

All in all tho like I said (all things considered), so far I'm a happy camper.

Kevin

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So per the chart above, if I switch to high lamp mode on my RS500, with my manual iris at -15 , and Auto1/2 set, it will give the best of both worlds ( ansi and dynamic contrast ) and less image treatment ?

Are any of you running in high-lamp mode on the lastest JVC's ?


~ Andy

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Mozen,

Have you seen differences between the last models and this year's JVCs as far as how dark a scene had to be before the DI closes down or how far it closes down? For instance, with Iris -15 and a checkerboard of 5% video level on black like on the 2nd edition of the Spears and Munsil disk or just a 5% window on black?

Thanks,
Darin
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Mozen, thank you very much for your excellent, detailed write up!
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Mozen go bye-bye?

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Quote:
Originally Posted by Mozen View Post
PDF attached.



Key and Notes:
Black Image BL – The black level – in lux – of a totally black scene or image as described above
Dark Scene BL – The black level – in lux – of a dark scene that is not a total fade to black. See above for description.
Peak Lumens – This is the peak output of the projector in lumens.

[B][I]
.
Excellent write up and detail. Very easy to understand.

Just one question if the peak lumens are held back by the Ap position then shouldn't the the max contrast for your last two items listed above be lower? Your black image and dark image are the same but your peak whites would be less as held back by the -8 and -15 min Ap position.
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Quote:
Originally Posted by Frank D View Post
Excellent write up and detail. Very easy to understand.

Just one question if the peak lumens are held back by the Ap position then shouldn't the the max contrast for your last two items listed above be lower? Your black image and dark image are the same but your peak whites would be less as held back by the -8 and -15 min Ap position.

Well spotted, this is correct.

The peak lumens seems right in the table for these last two lines, but the dynamic contrast should go down accordingly (it's only the native on/off contrast that goes up as you close the iris down, dynamic contrast and ANSI - simultaneous - contrast go down).
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There is like Frank D says something wrong with this report as well. The contrast is actually lowered compared to setting manual iris at 0 with the DI on when it is sat to a lower value and lowest when sat to -15.

My X500 had around 370000:1 with the manual iris sat to 0 and the Di on and around 150000:1 when the manual iris sat to -15.
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Quote:
Originally Posted by Andreas21 View Post
There is like Frank D says something wrong with this report as well. The contrast is actually lowered compared to setting manual iris at 0 with the DI on when it is sat to a lower value and lowest when sat to -15.

My X500 had around 370000:1 with the manual iris sat to 0 and the Di on and around 150000:1 when the manual iris sat to -15.

Yes, this is what I said above
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Quote:
Originally Posted by R Harkness View Post
Excellent work Mozen! I'm among many here
who I'm sure really appreciate this write up.

There is only one thing puzzling to me, since I
own the new RS600 which replaced my RS57:

Your description of the (new) DI is how I hoes it would
work, but yet it doesn't really seem to. Your description
matches how the DI in my RS57 worked: i could
have the manual iris set as high as I wanted for
bright scenes, and for most dark scenes the DI
would close down making it look like the black
levels I'd get with a closed manual setting. So
a "best of both worlds" as your description seems
to depict.

But with the RS600, if I set the manual iris to a brighter
setting, say - 6, without the DI I get raised black
levels. And even putting the DI on doesn't seem
to change this much - most, almost all, dark scenes
display those elevated black levels. Only full
fade to blacks seem to engage the DI at all, or
very rare super low APL shots. So the "best of both
worlds" benefit I got from the RS57 no longer
occurs with the RS600 (which has been probably
my main disappointment hhis far).

The only clue is perhaps in your report: that there
is little manipulation of the image with lower aperture
settings, and of course with the RS600 my aperture
Is set lower than it normally was with the RS57.

Still, your report suggests that nonetheless the DI
should be shutting down to about -15 for
dark scenes no matter where I set the aperture,
and if that where the case I shouldnt have these
complaints since, when I set the iris anywhere from
-13 to -15 and leave the DI off the black levels
look beautiful.

So...I remain confused.
Hi- let me explain your issue. The RS600 will have a better black level on MANUAL (no DI) at -14 vs AUTO at -6. Here is why. The RS600 has two irises. When you set the iris manually, it adjusts BOTH irises. When the DI is activated AKA Auto, it only dynamically adjusts one of the two irises. It does not dynamically adjust the rear iris. I hope this makes sense. Im going to make a revision to the writeup detailing this more and also correct any typos. Additionally, the dynamic contrast is actually better at Auto -6 than it is as at Auto -15 on the RS600.
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post #18 of 49 Old 12-22-2017, 11:09 AM
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Hi- let me explain your issue. The RS600 will have a better black level on MANUAL (no DI) at -14 vs AUTO at -6. Here is why. The RS600 has two irises. When you set the iris manually, it adjusts BOTH irises. When the DI is activated AKA Auto, it only dynamically adjusts one of the two irises. It does not dynamically adjust the rear iris. I hope this makes sense. Im going to make a revision to the writeup detailing this more and also correct any typos. Additionally, the dynamic contrast is actually better at Auto -6 than it is as at Auto -15 on the RS600.
but would you say Auto 6 or manual -13 has the best look or is it a matter of taste and sacrificing one or the other ( black or peak white ) this is a old thread but missed it and find the information interesting now that i have a RS540 , with HDR i just leave everything open low lamp Auto 2
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but would you say Auto 6 or manual -13 has the best look or is it a matter of taste and sacrificing one or the other ( black or peak white ) this is a old thread but missed it and find the information interesting now that i have a RS540 , with HDR i just leave everything open low lamp Auto 2
Let me ask you first, whats your screen gain and size? Projector distance to screen?
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post #20 of 49 Old 12-22-2017, 11:38 AM
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Let me ask you first, whats your screen gain and size? Projector distance to screen?
its a Seymour AV 108.7" 2.35 screen with a real gain at about 1.0 , the projector lens is about 13.7 feet from the screen
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post #21 of 49 Old 12-23-2017, 08:53 AM
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post #22 of 49 Old 12-27-2017, 09:18 AM
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its a Seymour AV 108.7" 2.35 screen with a real gain at about 1.0 , the projector lens is about 13.7 feet from the screen
My setup is about the same as yours and when I had my JVC RS420 professionally calibrated the iris was set to -6 for 16 foot lamberts.
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post #23 of 49 Old 12-27-2017, 12:49 PM
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My setup is about the same as yours and when I had my JVC RS420 professionally calibrated the iris was set to -6 for 16 foot lamberts.
thanks for the info ! i take it its -6 with Auto 2 ? i must say i'm torn because -11 manual has a darker but rich look to it

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post #24 of 49 Old 01-06-2018, 07:11 AM
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thanks for the info ! i take it its -6 with Auto 2 ? i must say i'm torn because -11 manual has a darker but rich look to it


Yep -6 with auto 2 most of the time. The setting on your iris is just to get the luminous of the image where you want it. Your screen is brighter than mine so -11 might be about the same as mine at -6. Most people like 16fl but some people like it brighter or a little darker.


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post #25 of 49 Old 01-07-2018, 04:07 PM
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Yep -6 with auto 2 most of the time. The setting on your iris is just to get the luminous of the image where you want it. Your screen is brighter than mine so -11 might be about the same as mine at -6. Most people like 16fl but some people like it brighter or a little darker.



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What is your setup ?
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post #26 of 49 Old 01-08-2018, 06:48 AM
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What is your setup ?
My screen size and distance from projector to screen is almost the same as yours. The only big difference is my screen which is a Center Stage UF that has a 0.8 unbenchmarked gain.
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post #27 of 49 Old 01-14-2018, 04:54 AM
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Quote:
Originally Posted by Mozen View Post
Hi- let me explain your issue. The RS600 will have a better black level on MANUAL (no DI) at -14 vs AUTO at -6. Here is why. The RS600 has two irises. When you set the iris manually, it adjusts BOTH irises. When the DI is activated AKA Auto, it only dynamically adjusts one of the two irises. It does not dynamically adjust the rear iris. I hope this makes sense. Im going to make a revision to the writeup detailing this more and also correct any typos. Additionally, the dynamic contrast is actually better at Auto -6 than it is as at Auto -15 on the RS600.
I have an X7500 (not sure what the equivalent RS number is) and I've noticed that the fade to black doesn't seem as deep as when I use Auto 1 compared to Auto 2. Previously I'd always used Auto 2 with my X500 and thought the fade to black was no different between the modes and that Auto 2 was preferable due as I barely notice it in action in terms of side effects.

Has this anything to do with the rear iris not being dynamically adjusted or some other reason, or perhaps I'm mistaken about the lower black level in Auto 1 (I'll have to measure it at some point with my sensor facing the projector lens).

FWIW I'm using -8 for 2.40:1 content zoomed to my 3 metre wide Seymour XD screen (I'm happy with around 13-14fL for SDR content).

"Don't believe everything you read on the internet". William Shakespeare 1615
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post #28 of 49 Old 01-20-2018, 06:41 AM
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Iris vs Calibration

Hello,

I am having calibration done to my JVC X590 on Tuesday. I know that changing from a high lamp mode to low lamp (or vice versa) will affect calibration. My plan was to have the calibrator use low lamp mode.

What about the iris? Does this have an effect on calibration?

Setting the iris to -15 and then Auto2 is how I have been typically running it as that seemed the most comfortable. My room is light controlled, no windows, dark paint on walls and the screen is under a 12" bulk head painted in the dark colour as well.

Do I calibrate using these settings or bump up the iris to say -12, -8, or leave it at the default (0) in low lamp mode and then dial it down once calibration is done?

Sorry for all the questions, hopefully someone can provide some insight.

Thanks.
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post #29 of 49 Old 01-23-2018, 02:13 PM
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Quote:
Originally Posted by ln46a6502008 View Post
Hello,

I am having calibration done to my JVC X590 on Tuesday. I know that changing from a high lamp mode to low lamp (or vice versa) will affect calibration. My plan was to have the calibrator use low lamp mode.

What about the iris? Does this have an effect on calibration?

Setting the iris to -15 and then Auto2 is how I have been typically running it as that seemed the most comfortable. My room is light controlled, no windows, dark paint on walls and the screen is under a 12" bulk head painted in the dark colour as well.

Do I calibrate using these settings or bump up the iris to say -12, -8, or leave it at the default (0) in low lamp mode and then dial it down once calibration is done?

Sorry for all the questions, hopefully someone can provide some insight.

Thanks.
The iris does have an effect on calibration as well as where the manual iris is set. It's best for the calibrator to target the ftL you want for the calibration. Find out how you like the brightness now and he can target that ftL. The auto iris should be turned off during calibration and turned on afterward if you want to use it. You really don't want to change the manual iris setting after the cal because that affects aspects of the cal particularly with greyscale and gamma. I'm not sure who your calibrator is, but make sure he understands these things.

Last edited by DavidHir; 01-23-2018 at 02:16 PM.
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post #30 of 49 Old 03-13-2018, 01:58 PM
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What does a DI artifact look like on these machines? Can it be mistaken for a bulb flicker? I occassionally see a quick change in brightness level that quickly corrects. It's repeatable but if I turn the DI off I don't see this behavior. Is this DI artifact or is my unit malfunctioning with the DI? I have the 540.


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