New High Contrast High Power Discussion Thread - Page 3

I was between 10 and 11.5 feet from my HP screen. (105" diag). I didn't need to be boozing to see the brightness shifts. I was sitting on a normal, single person chair. My back can get sore if I stay in the exact same position for long periods of time. So I'd go from leaning on side of the chair arm and after a while shift and lean on the other side. I guess this would move my head a couple of feet or so, but I could always see the image brightness shift every time. Drove me a bit nuts. I have a to-the-inch 3D computer model used to design my theater room and I took the measured/stated viewing angles of the 2.8 HP screen and plotted them to my room, measuring degrees of viewing angle from my seats. It turns out it was entirely predictable I would be able to perceive changes in brightness even with such relatively small moves. (I think the brightness change was something like a 20 percent drop when I'd shift my head).

As usual...sensitivity to these things vary....(I can only imagine my reaction to the even narrower cone of the new gray version).

Most people don't see the texture on the HP screen either. I found the HP screen generally very clean looking and only occasionally thought I spotted some texture, whereas I believe you found it more objectionable.

I've listed my 110x62 (126"diag 16x9) HP2.8 for sale in the AVS classifieds in case anyone is interested. Really hate giving it up (have had it 4 yrs), but have decided that I really do want to go larger.

Well, I've done some more viewing of the HCHP and new White HP samples, placed at the 4 corners of where my intended screen (128x72) would be. From my sitting position, there is noticeable variation in brightness of the HCHP at the 4 corners, but not in the White HP. And in contrast to observations of some others, the White HP is slightly brighter than the HCHP; but this would not be a concern, it is the brightness variation that is.

I.e., the narrower viewing cone is an issue for my arrangement (described above). Since I have black fabric on my ceiling and side walls out about 7 ft from the screen wall (and also, of course, on the back wall), I don't really seem to have any issues with reflected light. (I don't with my present 119x62 HP2.8 screen.) I would get a 2.8 White HP in the larger size if it were still possible.

My samples arrived this morning and i'll give some impressions later on. I can't fault Dalite's service here - I requested a sample on wednesday and it arrived on saturday morning in the UK!

If only Dalite products could be bought over here - they'd make a killing.

Your observations of the HP being slightly brighter to the HCHP are not in contrast to what has been reported assuming you made this determination with the screens in the corners, or were they placed centrally for that?

You're right--they were at the corners. I haven't tried it in the center since i don't want to tape anything to my present screen.

Anything new ?

I received my samples today and put them under a machinist microscope to see what was what.
I compared the old 2.8, 2.4 and HC 2.4.
The images were taken with a 4MP camera that does not have manual focus so the are not the best. You can not compare color, they look very much the same under this cheap microscope. However my view is better and I can tell you the HC 2.4 is just 2.4 with a gray emulsifier. As you can see, 2.8 had micro beads of the exact same size closely packed with little sign of the backing emulsifier. The 2.4 and HC are comprised of 3 different sized beads with the largest smaller than than the 2.8. There is also considerable room between beads compared to the 2.8. This is what gives the 2.4 a little bit better off axis gain. The scale of the scope is .02mm so the 2.8 beads are about .05-.06 mm. 2.4 and HC are .02-.04. I have no idea of the accuracy of the scope but you can at least see the difference.
If the wife lets me hang the samples tonight I will let you know my observations.

Here is the link to the photos.
Dalite HP Fabric Microscopic Comparison & House Hunters

I really enjoy your microscopic photos of these screens. The 2.4 and HC definitely look to be the same bead size and density so I'll chalk up the slighter more on-axis gain of my 2.4HC sample to manufacturing variances.

Hung the samples and watched some TV snapping photos.. didn't alter the photos but did play with exposure trying to show the difference. Wife and I would take HP 2.4 if we were not going to do a lot of lights on viewing other wise HC 2.4 is a bit better with darker darks and darker lights as well.. Photos were taken from my normal viewing spot, wife is off axis to my left. We love our 2.8.. I will take weak blacks with pop any day!
Left 2.4 Right HC 2.4
Dalite HP Fabric Microscopic Comparison & House Hunters

airscapes,

Very interesting! Can't figure out why the HP HC has more directionality than the regular 2.4 from these photos though. They seem to have the same bead size and density. If the only difference was the colour of the substrate they would behave similarly but the grey being dimmer. Something else is obviously at play here. Are they perhaps differing in the back coating of the beads? Maybe the HC has a mirror-like coating whereas the regular 2.4 has a matte white one which disperse the light to a larger degree?

I agree with you about the HP2.8, and don't think they have 'weak blacks'. As has been argued and discussed ad infinitum, it is the pj (not the screen) that determines o/f CR. A screen like the HP2.8 is simply like the same pj (with the same CR) but more lumens; a 1.3 gain screen, then, gives the same o/f CR with this pj, but effectively fewer lumens. Since we all seem to want more lumens (actually ftL), using a high gain screen is a no brainer if it doesn't produce any undesired artifacts for your specific setup, e.g., hotspotting [not an issue for the HP], inability to locate the pj in an optimal position, or too narrow a viewing cone for your seating arrangements.

Thus the HP2.4 is not as desirable as the old HP2.8 unless you need the wider viewing cone. Similarly, the HCHP2.4 is not as desirable unless you have ambient light conditions that might be moderated by the HC's reduction of reflected light.

The only photo you provided which any comparisons can be made is the full white shot #990 and that shows the HCHP (right) to be slightly brighter than the 2.4. I'm guessing that photo was captured using a flash?

No flash was used but it may have been over exposed a bit after all I was not pausing, just trying to snap when the screen was still.. I think that white shot was a commercial ending.. truthfully I did not even look at the photos, just dumped them and uploaded them.

The HC has a lesser viewing angle because it is a higher gain. They are both an overall 2.4 gain but the HP has a white backing which we will call a 1.0 screen with a 2.4x optical coating. The HC is a gray backing and without the optical coating is less than a 1.0, I'll take a guess and say it is .8 screen, which means its optical coating is a 3.0x gain to give an overall 2.4x gain. They could still do a 2.8 with smaller beads if they wanted to but their are tradeoffs of course.

This is common with many screens look at the Firehawk and the Studiotech 130 and compare their viewing angles. The ST130 is an overall slightly higher gain but has a much wider viewing angle because of its white base vs. the FH's gray base.

Da-lite as well as Stewart and other companies went to smaller beads because when 1080P became available the pixels were smaller than the beads and would cause more distortion. All screens with gain cause some distortion, so it is not criticizing anyone's screen. If you compare a reference screen like the ST100 and any optical coated gain screen up close and examine the pixels you will see the difference as the edges of the pixels won't be a crisp and some color distortion.

Further to Drexlers post I peeled back the coating on both the HCHP and the normal 2.4 to expose the backing. Interesting finding, the 2.4 has a gray backing fabric and the HCHP has a white somewhat pearlescent backing fabric. Both materials appear to fiberglass but can't I find a lighter to test right now. The first photo is a close up of the HCHP backing. I'd hazard a guess the color/reflectance of the backing at least aids in directionality of the top layers plus plays a part in the peak on-axis gain of the screens. The gray base for the 2.4 likely the cause of the drop in gain from the 2.8, the white base of the HCHP the reason it retains it's high gain (very slightly higher than the 2.4) on axis despite the gray emulsion.

Perhaps there is some kind of optical coating on the screen?

I got my sample today. It is a 2'x2' so maybe I can do some interesting things with it. My first impression is that it does not look very gray to me.

A bit of an OT question, but since a lot of HP enthusiasts are here it's a good place to ask:

Do any of you use (or have used) a pulldown HP screen (e.g., the Model C) in a large size (> 110"W, say)? Reason I ask is that if I do replace my present 110"W fixed frame (DaSnap) HP with a larger one (128"W), it would be much easier to install a Model C rather than a fixed frame screen (as well as about half the price). I have black material on the screen wall, so the screen basically disappears, thus esthetics is not a great issue. Main thing would be about winkles, but I know that the retro-reflective HP tends not to show these even if they are there, and also that the relatively stiff HP material tends not to wrinkle. The screen would be pulled down essentially all the time, i.e., no raising and lowering it.

Any experience or thoughts about this would be appreciated.

I had a pulldown HP. Wrinkles and waves were a bit of an issue with panning. With pans, you could sometimes notice the waves. Other than that, no issue.

Hmm. You 'had' one, but gave it up? Which model, what size? (Thanks for the feedback!)

I've had two pull-downs (model c's, one 133"diag and don't recall the other size) which I eventually converted to fixed applications and my experience echoes Lawguys. Waves will develop if they aren't there from the get-go and these waves are visible but not from varying brightness due to the wave gully angles like you'd see on a angular reflective screen but from projected image distortions during pans ie: straight line will bend and distort through the waves which is visible. Whether you find these minimal artifacts bothersome I can't answer. FWIW I no longer use my HP either, it's rolled up in the closet.

I didn't give up the HP because of wrinkles. The panning thing didn't bother me. It was a 106" HP - the original 2.8 kind. I forget whether mine was the model B or model C. It was the cheaper one.

To be honest, one of the reasons that I switched was because I preferred the look of a fixed frame screen. This is, of course, subjective.

Interesting, obviously the perceived grayness will vary depending on a few factor but in general my perception of mine is similar to this photo.

Mine does not look that gray. But, it looks grayer when viewed at an angle. Plus, I am at my office and it is bright here.

OK, thanks to you and LG. I agree that the fixed frame looks neater, and if they really do do a better job PQ-wose, I suppose I should just deal with the hassle of installation if I go the upgrade route.

Sounds like a Black Diamond screen on steroids.

Still I would love to see what it will look like.

Why do you sat that?

I'd think it's more like the BD is a HCHP on steroids, with a price to match.

Tensioned roll down screens are a good option too. You avoid the problems with waves. From what I remember, the HP is not available tensioned, at least it wasn't when I was looking. Also, cost go up pretty dramatically with a tensioned screen.

Ideally, I would have a motorized - ceiling recessed - Black Diamond but it does not exist at the moment.