New High Contrast High Power Discussion Thread - Page 2

It's interesting the effects of different screens, isn't it?

When I had my HP (2.8 gain) screen up and was comparing it to essentially a neutral gain white screen, the trade offs ebbed and flowed with program material. (This was even before my room was well treated for reflections, as it is now).

The added brightness of the HP screen made for a perceptually sharper, more dimensional image particularly on brighter scenes without too much dark area (the more dark the image, the grayer and less dimensional the image on the HP screen appeared). Darker scenes looked more convincing on the lower gain screen, due to the dimmer picture.

Overall the neutral gain screen never quite reached the heights of "wow" of the HP screen on certain scenes. But there was an overall sense of solidity to the image, anchored it seemed by the deeper black levels, that made for a more consistent satisfaction for me. That was true even as I envied what the HP could do with lots of scenes. (That's skipping my issues with viewing angles as well).

So, always a trade off.

But as long as you don't need a really big image, it seems you've got a bright enough image on the BD screen, while benefiting from the deeper black levels and better preservation of contrast, which sounds like quite a good trade off.

Rich,

Well, you have to factor in the projector in the equation as well. If you have a low contrast projector then yes, the HP will appear grey in really dark scenes. However, if you have a projector with very high contrast they will still have deep blacks. I.e. your RS20 will have deeper blacks on a dark scene with the HP than most other projectors would have with a unity gain screen - everything else being equal and no ambient light present. The higher the contrast on the projector the less drawbacks you will get in dark scenes. Ultimately with infinite contrast and you'd get none.

The HP just amplifies the light output, dark and bright scenes alike. It will be like having a brighter projector, which normally is not considered a bad thing, no?

Also, you can always adjust the brightness at the projector by using an iris or a filter to cut the light output. Too bright can always be dealt with, too dim and there's nothing much to do.

Tonight I've been playing again with the samples I have of the new HC and white HP2.4, 4 pieces of each. I have them stuck up on the white (since I took down the black fabric on the screen wall) wall at the 4 corners of where my larger, 128x72, screen would be. There is a HC and white piece in each corner.

I've looked at grayscale test patterns, from 10% to 100% IRE, and moved my head 2 to 3 ft each to side of my primary seat (which is near the screen center). Unfortunately this has shown that the HC material has too narrow a viewing cone for me: the sample pieces on the right and left sides take on VERY different brightness when I move only 2 ft off center, while the white HP pieces on the left and right sides maintain the same brightness. This was not a subtle effect and is quite definitive, at least for my setup.

So if I do get a new, larger screen, it looks like it will be the white HP2.4. (Any body interested in buying a 110x62 HP2.8, DaSnap fixed frame?)

I received my sample of the HCHP today along with a Da-Mat (just for a baseline gain and to compare to my screen. Gotto feel for that Matt guy, not dumb just misunderstood). For a few quick observations I'll first state I was surprised how much darker this material was than the 2.4 or 2.8 when viewing under a typical room lit condition, a good precursor to the benefits of this screen. The screen material is the same as the 2.4, not the smooth 2.8. When taped on my screen with the 2.4 and 2.8 with all the room lights it's quite obvious this screen is very effective at re-directing high levels of ambient light away from the viewing area and maintaining much lower black levels than the other screens

Turning on the projector and comparing the screens at the full on axis gain shows the 2.8 to be the brightest followed by the HCHP, then the 2.4. Assuming the 2.8 is actually a 2.8 gain and the 2.4 is 2.4 I'd guess the HCHP is about 2.55. While seated in the back row the pj is mounted about 30 inches above eye level and from the central on axis seat the HCHP has near the exact gain as the 2.4 screen, moving to either of the two side seats at 10 degrees of central axis and the HCHP's gain is slightly lower than the 2.4 but still brighter than a 1 gain screen (in the photo below I've imposed a small square of the 1 gain screen onto the HCHP for comparison, it's not subtle). Moving more than 12 degrees of axis with the pj 30 inches overhead and the gain drops quickly.

Regarding screen texture, with the 2.8 I became annoyed with it because of a paisley type texture I could see on brighter scenes and this caused me to change my viewing philosophy somewhat but I noted the 2.4 sample I received had less of this optical texture and I thought it was a better screen which provided a smoother looking image at typical viewing distances. The new HCHP has more texture than the 2.4 but the texture is slightly different, it's not like what I've found on any of the 4 2.8's I've had or the 2.4 but has more of a very subtle sparkly sheen which reminded me of the Studiotek ST130 G3's texture (had one). To confirm I pulled out the 130G3 sample I still have and yes, the optical texture of the HCHP has a remarkably similar signature as the Studiotek, which is good news for most.

This screen would be a superb choice for those looking for added gain, are battling off-axis ambient light issues or just like to watch with a light or two on, but have a relatively narrow viewing area of 3 maybe 4 (pushing it) seats wide . It's brighter than the 2.4 on axis (both) and the same brightness at 10 degrees off axis (20 degree viewing cone). With the PJ 30 inches the HCHP offers the same brightness on axis and slightly less at 10 degrees off axis. Outside of this and gain drops like stone.

Basically, all the viewing caveats/conditions you find for the 2.8 and 2.4 also apply to this screen. The flip side though is outstanding ambient light re-direction for black level retention. Though I couldn't capture the effect with a camera (poor black level differentiation) with all the ceiling lights on (two just in front of the screen) in my dark room and viewing the screen at an angle which equalized brightness, the black level of the HCHP appears to be about 1/3 that from the 2.4. while offering the same if not a brighter top end. All in all an impressive package which performs as many have previously speculated a gray HP would. In case you go looking at my HT, the photos in my link have not been updated to my newer HT scheme.

In the following photos the top sample is the 2.8, the bottom sample the 2.4, the smaller bottom left is the Da-mat, and the smaller central is the HCHP.

Hughman: Good and detailed description! Interesting how different ones of us fix on different aspects of these screens and draw different conclusions!

I think the one thing that influences my observations is that I'm sitting very close to a large screen. I.e., I have the samples at the left and right edges of my intended screen, 128"W, and I'm sitting 11ft (132") from it. My RS20 is at its shortest throw, but since I'm so close (I've gotten hooked on the BIG pic!) it is still about 3 ft behind my head. So if I lean over to the left or right--e.g., moving my head only 1.5 ft, say--I get enough of a change in viewing angle that the brightness of the HC HP samples at the left and right become very noticeably different, while the brightness of white HP2.4 samples change not at all (to my eye). So in my configuration, the extreme narrowness of the viewing angle for the HC HP is a serious detriment, enough to rule it out for me. The 4 samples of the white HP2.4--at the 4 corners of my intended 128x72 screen--appear totally uniform, and in fact essentially as bright (as my eye can tell) to my old HP2.8 screen.

So for my configuration, the white HP2.4 is the obvious choice. The wider viewing cone of it compared to that of the old HP2.8 might even make it better than the old one (for me).

Hughman I thought the HP is free of any visible screen texture from what i have been told here in the forum. I was hoping the new HCHP will be the ideal candidate to replace my venerable Greywolf II, which is notorious for its sparkly sheen but otherwise gives a great image.

Any thoughts from others? Thanks.

Very interesting!

I think that this will be an excellent screen for many people.

I have yet to receive my sample but based on what others have written, I am optimistic. From Hughman's picture, the HCHP seems grayer than I imagined. Also, both Hughman and millerwill suggest that the 2.4 HP and HCHP are similar in brightness (if Hughman thinks the HCHP is a little bit brighter).

So, a relatively dark gray substrate with a good amount of effective gain must have a really large amount of actual gain. This is so because gray absorbs light. To compensate for the gray substrate's light absorption, the actual gain has to be 2.4 plus whatever amount of light the gray absorbs. So, maybe the actual gain of the screen is 3+ (just a guess).

I wonder how this is accomplished. With an angular reflective screen, an optical coating (or coatings) is applied to the screen. This coating reflects a lot of light but the more it reflects, the narrower the viewing angle becomes and the more visible the coating becomes. But, the HCHP is a retroreflective screen that gets its gain from glass beads. Maybe there are simply more glass beads in the HCHP than in the HCHP. But, maybe it is more than that. The description of the HCHP on Dalite's site says that it has a "highly reflective top surface." This may be another way to describe the glass beads or it may mean that some kind of optical coating has been applied to the screen. So, it could be a hybrid angular reflective/refroreflective screen. Just a theory.

However it works, the large amount of gain restricts the viewing angle more than the HP does. This further restricted viewing angle means that the HCHP will reject more off axis light. No one has yet mentioned any visible texture. That is good and a definite improvement over angular reflective screens (and suggesting that there is no reflective coating applied to the screen).

Both millerwill and Hughman focus on viewing angles. A few points here. If the HCHP is like the stock HP, there may be differences in brightness from seat to seat, but each seat gets uniform brightness over the entire screen. If so, this is a definite improvement over some angular reflective screens in which the image may not be uniform for seats in some locations. Also, even if you can see changes in brightness by doing as millerwill did - leaning left and right in a seat - people generally don't watch things this way (I don't anyway ) So, some difference from seat to seat could be an acceptable compromise IF the light rejection properties of the screen improve image quality overall.

Again, this is all theory because I have not yet seen this screen.

The sheen or texture from the HCHP is very subtle, but it's difficult to ascertain the overall impact from a small sample. Despite that the sheen is on a magnitude far far less than what you'd see from the Greywolf, and many may not notice it at all.

Agree, this is a great screen.


Below I've attached a photo taken with flash which will show the screens maximum gain differences. The HCHP is centrally located within the 2.4 and does show to be brighter than the 2.4.



Actually above I noted I feel the texture is ultimately similar to the ST130 G3. However, with only viewing small samples of both that impression may correlate non-linearly as the screens increase in size.


That's a good summary, and it should also be noted that even with the projector 30 or so inches overhead staying within a 20 degree viewing cone (3 chairs 12 feet from screen) the gain will be higher or about the same as any high gain angular reflective screen. I'd guess it to be from 1.5 to 2.4 gain under that scenario.

No question, sitting at 11 feet from any size screen will put the adjacent side seating greater than 10 degrees off axis and closer to 15 and that's where the gain drops quickly. My photos in my first post and impressions were gathered sitting with my eyes about 15.5 feet from the screen which keeps the viewing cone from three seats within about a 20 degree cone (10 degrees off axis each side.) When I find myself swaying back forth while watching movies it's time to put the bottle down and head to bed.



The 2.4 definitely has the flattest (less peaky) viewing cone of the three.

Truth is that I am less interested in gain than I am with light rejection and contrast preservation. I am trying to figure out how to test these things with a small sample. My old HP lit up my room even though it was treated in many areas. This often did bad things to the image on screen. I am hoping that the HCHP would mitigate this.

I am very interested in looking at 2.4 and HC 2.4 under a microscope to see if the new produce is just 2.4 with a gray emulsifier or if there are other differences. From the description that millerwill gave it could be just 2.4 with gray emulsifier. From my experience comparing 2.4 and 2.8 screens side by side. 2.4 has a steeper drop off of the gain provided by the glass beads than does 2.8. However with the large amount of white emulsifier it has a better off axis gain. If you were to make that white surface gray, you would see a very sharp drop in gian as soon as you were out of the bead cone and the 2.4 white would stay at a gain of 1. Does that match what you are seeing millerwill?

If I understand you correctly, I don't think that your explanation is right.

Gray absorbs more light than white. So for a gray screen to have the same effective gain as a white screen, the gray screen must really be higher gain than the white screen.

If the HCHP was just a 2.4 HP with a gray substrate, the gray version would be dimmer than the white version. This is not the case. They are around the same brightness. To me, this suggests that the HCHP probably has more/different glass beads and/or some kind of optical coating that increases the gain in the same way that the coating on an angular reflective screen increases gain.

Here are few photo comparisons up close, this post is of one comparing the surface of the HCHP to the 2.4. plus one photo showing the screens propensity to hotspot but only at an off-axis angle, the light appears to have angular reflection on the back side of the ridges, this photo is about 45 degrees from the light source.

The photos in this post show the varying perceived screen textures up close depending on the viewing angle from the light source. The last photo is at approx on axis to light source and this photo depicts some of the same optical texture I've noted in both the 2.8 and 2.4 versions. As viewing angle decreases the viewable screen textures transitions from the screens physical texture to the gain components optical texture.

photo 1- approx 90 degrees
photo 2- approx 45 degrees
photo 3- approx 0 degrees

What happens when the viewer is at zero degrees to the screen and the light comes from off axis at varying degrees?

Good idea, previous photo were with the camera at about 45 degrees to the screen. With the camera on axis or at 0 degrees (or 90 depending on your POV) directly in front of the screen the texture changes somewhat there's far less transition to the direction of the optical texture becoming apparent as the light source approaches 0 degrees.

From these pictures, it does not seem that the HCHP is rejecting much off-axis light. Hmmm . . .

I think it's the camera, all that's required to confirm it's off-axis light rejection abilities is the first photo I posted showing all the screens with all room lights on and the photo with the camera flash on depicting the relative gains of the screens on axis. Everything else is pretty much a waste of bandwidth let alone time which I seem too have too much of.

Regarding the gray portion of the screen, it appears to be the emulsion binder for the retroreflective beads as opposed to a grey base fabric. It should be interesting to see the material under microscope and I look forward to airscapes report on this.

One more thing, the screen color when compared to the studiotek leans toward a blue/red (majenta) push while the 2.4 pushes more blue.

This is the most interesting and informative thread I've been involved with on the Forum for several months--thank all you guys! (I guess all we needed was a new product.)

I'm going to do some more viewing experiments tonight, but in the meanwhile did a little trigonometry for the fun of it. As I understand retro-reflectivity, the relevant angle is that between the lines from the pj and from your eye, to a given point on the screen; I'll call this angle alpha. So for my specific situation--128"W screen, pj at min throw (178", at horizontal center of the screen), and viewing distance (admittedly very close) of 11ft (132")--I have calculated the variation of this angle for various horizontal points on the screen and for various horizontal sitting positions.

1. Viewing position at horizontal center of screen: alpha obviously = 0 for a point at the center of the screen, and it is 6 deg for the left (and right) edges of the screen. So the HCHP should be quite uniform and essentially full brightness over the whole screen; nice.

2. Viewing position 24" to left (or right) of horizontal center: alpha varies between 0 deg (pj shining right over your head) to 14 deg. The latter angle I think will yield a significantly dimmer pic that alpha = 0, and this is what I want to check out more systematically tonight.

Now if I didn't sit so close--e.g., if I sat back at the distance where the pj is--things are different:

3. Sitting at the screen center (i.e., eyes right at pj!), alpha = 0 for all points on the screen.

4. And even if the viewing position is 24" to the left (or right) of horizontal center, alpha varies no more than a few deg about 6. So no problem.

So the viewing angle issue I'm concerned about is strictly due to wanting to sit close (~ 1.0 to 1.1 SW) But if I didn't want to do that, I wouldn't be thinking about a new screen!

From my above post, you can see that my concern is not the variation in brightness that one sees by moving your head around, but the variation in brightness at different points on the screen from a given (fixed) viewing position. I.e., the first statement quoted above is true only if the viewer's eyes are sufficiently close to the pj lens (which can't be achieved if one wishes to sit much closer than where the pj is located).

If you wish to maximize uniformity over your current setup looks like you only have two options: Either move the pj closer to sitting position or move the couch back towards the PJ and then get a much bigger screen to maintain same viewing distance/screen size ratio. If the HCHP benefits aren't being realized in your room however, seems more of an exercise of ocd, not saying that in itself isn't a good enough reason.

Okay. I see that now. This is unusual for a retroreflective screen.

Actually it makes perfect sense for a retro screen. The greater the offset between viewer and PJ the greater the gain differences will be from center of screen to screen edge. Here's a little diagram. Light travelling back to the PJ from the screen will be of the same gain regardless of where on the screen it comes from, the gain for the viewer at the screen center will match the light intensity reflected back to the source, but as the viewer gets closer to the screen relative to the PJ the angle increases between you and the max gain reflection from the screen sides therefore you are subject to the same off-axis dimming you'd encounter if you moved your seat further off axis.

But I can't solve my problem with either strategy above: the min throw distance of the JVC (which is about the minimum of any pj) is 1.4; i.e., the closest the pj can be to the screen is 1.4 (actually ~ 1.37) times the screen width. But if I want to have a viewing angle of ~ 50 deg (which I do), I have to sit at ~1.0 to 1.1 screen widths. 1.1 < 1.4 no matter what size screen I have.

I'll do some more viewing experiments tonight and report back.

Yep, that's it!

Ahh I see.

I rewrote that a few times and it still isn't all that clear .

Okay. I didn't think it through as respects millerwill's setup.

I am only familiar with BOC and a matte white flavour, my screen is currently in illinois , on its way to laredo to my customs broker, i estimate it should be here next thursday , i will report my impressions and try to take some photos then (almost meaningless but fun either way). I received my new cabinet/stand from the factory today it stands at 40" high and puts the lens of the Pearl right at 43 and a bit, so if i am right i should be quite close to the optimum .... We shal see, literally, lol!