Laminate Screen Material and Testing! - Page 20

To point out the obvious, Nickmo's recent photo above shows the laminate used has deffinate Hot Spotting going for it. Or against it as is the case.

It does not however seem to be of an issue with him even though such was pointed out to him before by Clarence quite aptly.

Noticing that deficet might actually occur overtly only when aprubt changes between color pallets occur (Sky to grey glouds to sky) or in the appearence of any highly reflective surface contained within the program material, resulting in a washout of detail. If bad enough, due to the use of excessive lumens or increased gamma settings, much detail and CR could go south. Or it might be quite noticable once decerned as being existant.

A case of "What you didn't know, didn't bother you". A "Spoiler' as it were.

So of course, one has to experience what is "best" to be able to adaquately judge what appears to be "less than...". Without that criteria however, one just might not notice anything at all and be blissfully satisfied.

In actuality, the central hot spotting is not any more, or less an issue than the disparity between the intensity of the lumens returning from the center, and the significantly lessor degree og luminosity produced by the perimeter. Even something not apparently noticable can still produce eyestrain after a short while. Eveness of light distribution across a broad area is something that should take just as much precidence as color purity, and contrast values.

It matter not if a low lumen PJ or a light cannon is used, the effect will always be present in some degree. So consideration should always be given toward using a material that does not exhibit such tendencies toward uneven reflection, or efforts must be made to mitigate such tendencies.

But if any such material exhibits such tendencies in a all too obvious manner, adjustments cannot be scailed accurately to offset a centrally located manifestation while leaving the edges unaddressed. This issue is made more an issue the larger the screen surface used.

Nope. The only real solution is the use of a material that exhibits more eveness of reflection overall. Something that truly distributes light across every inch of surface in as equal a manner as possible. Not an easy find, especially with PJ lumen levels rising as they are. The only sure way to offset these issues in the easiest and most affordably manner is through the use of truly "Flat hued" surfaces. Otherwise, one must look to the principles existant in other solutions, but those solutions are not relevant to this discussion.

BTW Nickmo, you did a great job on that Frame build. Poplar was a wise choice, for it resists warpage, and holds fasteners quite well. Although it is quite a bit more expensive and quite a bit thicker than the primed MDF Baseboard I use consistantly. I save the use of 3/4" high Trim for only really big screens of 120" or larger, for the "rise" is less noticable, and the dispersion of light sideways is more even when the light cone is more broadly projected. You'll find that you will have a deffinate shadow around the perimeter of the image to deal with, caused by the light hitting the 3/4" raised edges of the Trim. I use the curved edge of simple base Trim ( 1/2" wrapped in Black Velvet) to create what amounts to a edge that moves toward being almost flush with the screen surface. Or....if I rip off the "curve", I still have on 1/2" of a rise to deal with.

Whatever he said. Anyways, I'm using the DW with a Z4 with the iris opened up quite a bit and I have no hot-spotting. Numerous others have tried it and have none. Either the previous poster has some camera issues or something else is going on.

I haven't posted into this thread in a while but have been quietly watching it.

IMO the photos posted and by the posters own admission his photos and cam he used to take them was not the best of setups. He went as far as making a offer if someone wanted to help him take some with a better cam or view what he's seeing to contact him.

I like spyfy cant see how anyone viewing these photos knowing the setup was makeshift at best with a projector that's non calibrated can praise or condemn the materials ability to be used as a projection screen at this point.

I do agree with MM for a first attempt at a screen nickmo did an excellent job at building his screen and frame. I would encourage him to read thru the thread Tiddler did where all the on and off axis screen shots were taken and after he's all setup and calibrated. Also take some time and figure out how to take available light photos and maybe use a tripod or some support also when taking the photos.

If you need some help with taking the screen shots PM me or Tiddler and we can give you some pointers.

Some of Nickmo's hotspotting issues may be related to his screen size and the brightness of his projector (the area of a 37" x 66" screen is less than half that of a 110" diagonal screen).

Wbassett

The hot spot you see in the photo taken with the flash really means very little. The cams flash is extremely bright but more importantly the flash and the lens are only a inch apart and the photo was taken straight on. About all that photo shows is the nice looking job and to give us a rough idea of the shade of gray under bright light.

Very true. Just another factor that has to be entered into the mix before passing any conclusions.

Clarence: I've never heard of using the Posterize function of Photoshop to test a screen. Is this a standard test? I tried it with a few screenshots, and was able to produce the same "hotspot" results with just about any bright shot. Can you gives us some more background on this technique?

Garry

I don't see where nickmo mentioned using a flash. But if that's the case, then yes, that would explain the horrid hotspot.


I use it quite a bit to over-emphasize the raster patterns on pictures of tube faces when assessing phosphor wear or burn.

Hi everybody,
I have work/school today until 3:00pm pacific. After that I'll try to get a better camera setup and take some more shots. Also, in the screenshots with projector images I wasn't using a flash. I did use the flash in the "build log."

Thanks to everyone who praised my work, and to everyone with advice. I'll try to answer all your questions and get better pictures as soon as I get home today.

Designer White.


Actually my ceiling mount was delivered yesterday. I have one last thing to finish for the wife on a tiling project then I can start hanging the projector.

I forgot to mention that right now my projector room has tan walls and a white ceiling. I plan to eventually paint the walls and the ceiling a flat dark red wine color to cut down on reflected projector light.

The first batch of photos were taken with projector light only, the second ones with no image was a flash picture. I also saw the hotspot in the projected image and the drop off across the face MM was quick to point out. But I discredited both because I thought he said he didn't have his projector mounted yet and who knows what mode his cam was in when sampling a bright image surrounded with black. Many of these newer point and shoot digitals assume the center of the picture is what you want a proper exposure of and only read light levels at a couple of points.

If his projector was mounted at eye level or in this case cam level why try and analyze these early photos.

The gloss on the Wilsonart samples doesn't look to be any higher than on the Vutec samples I have. Can someone compare them to other manufacturer samples like Stewart, Draper, etc.? When I measured the gloss on the samples I have, it was about medium. I can see where it might have a problem with hot spotting, but I wouldn't think it would be any worse than a manufacturer screen.

Ericglo

Ok, I looked at some of the photos I didn't post from the build log and I found one that I could read the product number from.

HD did send the correct part. It's D381-350-60.

The projector is sitting on a shelf about 5' 7" off the floor. The pictures were taken with a Konika-minolta dimage Z2. I was standing about 1' to the right of the projector when I took the shots, so assume the camera was pretty close to 5' 11" from the floor. The bottom of the screen, now that it's mounted, is about 2' off the floor. That would put the center of the screen at about 42" off the floor. Should the projector be mounted higher? When I take new pictures should I be sitting in the viewing position or standing next to the projector or somewhere else?

Last night I watched some Underworld and Starwars IV and played Halo for a couple hours. The hotspotting is only noticible in scenes with a lot of white right in the middle of the screen. For example storm troopers and princess Leah(SP?) were especially shiny.

wbassett:
I agree that the cabinet is probably reflecting a lot of light back onto the screen. In fact, the entire area below the screen is much bighter than the rest of the wall when projecting, so this might be the part of the problem. Removing the cabinet is not an option (WAF). Is there a way to reduce the reflectiveness of its surface without ruining its color/appearance? I don't think my wife will want black cloth scraps on top of it when guests are over; neither do I, now that I think of it.

First thing to check would be the stock number of the Fashion Gray that nickmo is using. Wilsonart laminate comes in a lot of different gloss levels, and there's always the possibility of a screwup at HD or Wilsonart shipping - it should be D381-60.
I would also recommend cleaning the whole screen, as there may be something on it from manufacturing, etc that could raise the gloss.

According to Wilsonart, the gloss levels of D354-60 Designer White and D381-60 Fashion Gray are identical, so I'd have a hard time understanding why gray would hotspot and white wouldn't. Could be an issue of surface color vs specularity, but I'd have to give that some more thought.

It may also be a false alarm. It's amazing how quick some are to jump on the slightest potential flaw and go off on wild tangents. I don't think one should pass judgement on a screen based on some admittedly poor screenshots and a Photoshop manipulation before the projector is even mounted or adjusted. Perhaps we should wait for some more info.

Garry

I think your projector may need to be mounted higher? And yes you should take your shots from where your eyes are when viewing would be best. Find the recommended drop height for the 900U and go with that, would be my recommendation. I take it you are not going to mount it upside down as in a ceiling mount. The idea is to place the hot spot if there is one below where you normally view from. Think of it as the reverse angle of a line drawn from the projector to the center of the screen.

I'm with Garry on jumping to conclusions. I'm putting my money on calibration, cam angle and projector height right now. I think nickmo is really going to like his bullet proof screen.

One point was made and I don't know much about the Panny but that is a pretty small screen and the FL have to be up there. Is there enough in the calibration to knock it back?

First off, no pictures. My wife left the camera at work, so it'll probably be Friday night before I get any shots up .

I cleaned the screen with damp paper towels and extremely diluted Simple Green. I also covered the cabinet with left over velveteen from the frame and a dark towel. I then used DVE to adjust the brightness and contrast. I was able to turn the contrast down a bit, but the brightness stayed up around +12 to keep the "2% above black" signal visible.

After that, I made sure the lamp mode was set to "low." The screen is still hot-spotting, although it is a little reduced. Any bright scene has obvious shimmer in the center of the screen. The hotspotting effect is non-existent if I'm sitting on the floor.

I also noticed that the screen has incredible off-axis viewing angle. I was standing with one shoulder against the same wall as the screen, and the picture was still great!

that's all for now.

That tells me that if you raised the projector the hotspotting will be non-existent. At the present projector height it's like your screen is retroreflective and you're seeing the projector beam bouncing off your screen because the angle of the projector and your head when you're sitting on the sofa is too small. However raising the projector will change the angle of reflectance so that your screen will become more angular reflective which should reduce the hotspotting. Try raising the projector so height is the same distance above your head as if you're sitting on the floor, i.e, your head has to be inside the angle of reflectance. If you've every played pool you be familiar with the concept.

You are almost there. Unless you like sitting on the floor, then you are good.

There is another solution and if you like to tinker you can try this. Tilt the screen just a little out from the wall at the top. I know this most likely isn't the look you are going for I only mention it because others reading may have a similar problem and have a setup where doing this might help. If its not to hard to do this it could be a easy way to get a feel for how much you do have to raise the projector.

The higher you mount the projector the more likely it is you will want to turn it upside down. The reason being that most projectors are designed with the optics aligned in such a way that they can be table or ceiling mounted. Think of the light coming out of the lens and shooting uphill when its table mounted. If you ceiling mount it without flipping it the image will be on the ceiling. And if you set it at a steep angle then you will need to do a large keystone adjustment.

The wide viewing cone is nice IMO that's what my screen is like.

From what I'm hearing I think you should be able to drive the hotspot low enough to enjoy a good image. But the sheen on the laminate Could still be a little higher than what would be perfect.

I'm going to try inverting the projector today. I can't actually ceiling mount it because I live in an apartment. I'm going to Wal-Mart to find some sort of air circulation-friendly stand I can set the projector on upside down. Then I have to finish some hairy Numerical Analysis home work, after which I plan on taking pictures of the results.

This projector/screen setup has taken over my life!

Why not? A mount will create just a little damage. That is nothing that ten dollars of spackle and other supplies can't take of.


Is anyone living in or near Seattle buy a laminate screen yet? If so, then maybe you can hook up with Darinp2. He has a completely dark black velvet room and a light meter. He is probably not interested in buy one of these screens, but if someone took theirs over to his place then he could take some measurements. This would settle the amount of hot spotting issue, which is a significant question.

I think you said you mounted your projector on a shelf? Can't you add another shelf or elevate the shelf until it's at least the height of the top of the screen or slightly above?

What are you guys paying for the 5x10 sheet of Designer White? I called my local Home Depot and Lowes and they were priced at $155 and $180 Before tax and special order fees. That sounds much higher than you guys have been reporting. I'm located in the STL area.

I did that last night and still got hot spotting when viewing from the couch. The projector is in "desk" mode which throws the image up. In ceiling mode it throws the image down. Because I have it so high up in desk mode I might as well flip it over and run it in ceiling mode to see if there is a difference. Free to try, nothing to lose. If it doesn't fix the hotspotting, I didn't waste $$ on a ceiling mount.