Spot The Spider

Well I didn't vote but I will give my observations. I really don't care about AL tolerance but I do care about getting the BEST image possible in my HT. If that means going to a gray screen then so be it. So I will not vote for which one is better.

In your pictures Todd, remind you that my monitor is calibrated to RGB with Spyder and Adobe Photoshop CS3, I COULD NOT tell a difference between the two.

I then started to get frustrated that you didn't use your required (said in jest) sample photos. Most of those photos, until the last post, were not good represenatives for screen comparison. I think maybe only one or two had enough color/flesh/light/dark in the same area, but on two different paints, to gather a reasonable conclusion. Todd, those photos are horrible, even the untouched ones. Sorry, but I had to say that.

The last post had some very good symetrical screen shots to compare. I still COULD NOT tell a difference. If that's the point you're trying to prove (you usually have a point to prove), then it worked for me.

BTW, what is that last movie with the rather hot women dressed up all MidEvil and stuff.

Rob

Can't pick a winner from these. How about some shots with color bars?

I firmly believe there is a "depth" element that is impossible to show with screenshots, too. Any visual impressions? What's your preference?

Garry

Rob

Can I vote for the background screen? I like that the best.

Nice post. I was debating painting BW over my N8 gray w/ pearl-poly topcoat. But having seen these, I'll just leave well enough alone and keep enjoying my movies.

Oh, I voted "unsure".

they look the same to me

I got a little confused because if I couldn't figure out what one was BW and then you said if you are having trouble pick the one that looks best and call it BW. I was going to call the best one the poly. Hmmmm

Anyway I couldn't tell and like you said they are both to dark for your projector actually. One thing I have always found interesting about going gray was that a very slight amount of gray could give an outstanding improvement and the steps between shades are very slight. Too dark of course is worse than too light IMO. I tried to do a stepped approach and error on the side of light. that was a lot of my questions early on with the BW it looked to dark for the vast number of peoples setups. Small screens or bright projectors being the exception to the rule.

On a side note I blew my bulb a couple weeks back and ordered a new one last night and I should have it in 4 or 5 days. I'm actually excited to look at the observations again I made 2 years ago when selecting my screen gray and gain. Over those two years I have gained a lot of insight into the selection process. So it will be interesting how my eyes now view the fresh bulb. My plan was to always have room to add brightness as the bulb dimmed but at the time it blew I was still a long way from max brightness. So based on that maybe I could have went a little darker in the beginning with the gray. I do remember the first 200 hours being pretty white hot and some real color popping. So I might have to wait for that to pass before really taking a good look at where I'm at.

Very nice post Todd and you make all great points. As you have seen I have been holding back from filling in the posts I reserved in the DIY guide sticky thread. One reason for me holding back is some of the investigative work that has been going on and also my belief that it’s imposable to explain how to select a screen paint without first knowing the fundamentals of what happens when a projected image strikes a screen surface and then what happens when the image enters our eyes and is transmitted to the brain. What you call personal preference is in part how our eyes and brains differ in receiving these images. One of my constant jobs over the last few years of my mothers life as she suffered from macular degeneration among a host of other problems was to constantly calibrate her small LCD TV that she viewed from a distance of about 8 inches. Well wishers and visitors were always adjusting her PQ to display a image that was color correct to their good eyes. I would get a call at midnight that her TV was washed out and only showing black & white again. I would go over and max the gamma and push the brightness up to a point it resembled a bad 60’s drug experience (movie think, the doors). And she would be totally happy again. You have no idea how many Matlock’s I sat thru like that.

Back to color, sheen and texture. I have always liked at least one more unit of gray to pick from between the ones you mentioned above so if we recommend the “N” scales starting at white I like to go by .25 unites.
Sheen and texture IMO run hand in hand and in the case of a controlled texture such as canvas. (as you know I like for that reason) the texture IMO allows you to tolerate a higher level of sheen. Because the texture causes a scattering or diffusion on a much larger scale that the pigments in a flat paint would. Being able to have a higher sheen level combined with the good properties poly adds to the ease of application and leveling of the paint is most likely why I have been able to brush paint my canvas screens and end up with no blemishes. The thread count in the canvas was of interest to me a while back when a friend brought over a 1080P projector to demo on my screen. We thought the texture did an equal job with my 576 lines as it did his 1080 lines. Both projectors were DLP’s and in both cases SDE was eased, but with the 1080 you had to get within inches to see it ether way. my SDE becomes a issue on 110 inch screen at about 6 or 7 feet for my eyes. And no one complains at 10 to 12 feet ever.

As to one can call out by name paints that are neutral or taking in a recipe for a mix, they are both as easy to me and the issue I have always had with all the cross matching of recipes, or switching bases to get a different shade of gray is that these bases now as we now know hide pigments in varied amounts and also have different sheen levels in their flat state. I have always been of the camp find a few brands and bases that are in most communities and then tailor our 6 to 10 shades within a common base. There are all kinds of methods to cut down or build up mixes at home so a person thru experimentation could build his own test samples using just a couple cans of paint.

It boils down to getting the proper FL’s off a neutral surface, tailoring some kind of sheen to work best with some level of ambient light darker grays can be helped with sheen getting FL’s back up while helping to tolerate some ambient and also improving perception of ANSI contrasts.

having taken a closer look at the 4850 (with poly) and comparing it the BW...
i'm fairly confident the BW is on the right.

the reason is fairly easy if you look closer at the details...

1) the BW has ever so slightly better black levels than the reference 4850 /wp
2) the BW has ever so slightly better white levels than the reference 4850 /wp
3) the BW has ever so slightly better flesh tones than the reference 4850 /wp
4) the reference 4850 /wp has a noticeable poly sheen in the black levels that makes the black level performance less than the background screen in dark scenes... especially at the far left edges of the screen.

I have found like Todd mentioned that most screens do their best in the middle of their total range. For instance when I was doing testing between BOC and gray surfaces with sheen raised to its proper point, based on the projector being used, the BOC held its own with bright colors and skin tones. It was like both surfaces had similar qualities but the better screen had a slightly longer range at both ends, black and white. That extension was of little consequence when watching Cars but was when watching Lord of the rings or any dark detailed image. Allowing for that difference in preserving some of the ANSI contrast the projector was capable of with some ambient light was very noticeable. I felt at that time and I think I posted the difference my feeling was the gray out preformed the BOC by maybe 5%, at best.

What I see after studying the BW , Gray comparisons here is about 3 or 4 averaged RGB points improvement on the black end and maybe a point mismatch on the white end and that is really trying to see changes finer than frogs hair IMO. And those are the ambient photos where the source is in line with the projector light. So if sheen from poly is a little more retro reflective than sheen from metallic that could partially account for a point or two of the variance. Light coming from the side could act opposite and some of the extreme angle pictures point to this. At any rate an improvement of 3 or 4 RGB points into black equates to 1% or 1.5% improvement.
This is visible in the two photos shown but it should be noted that even in the maxed out brightness mode Todd did his tests in he was most likely falling short of lumens for both of these too dark screen samples. I know the reason he set the limit where he did was because he was given the level of the BW as a fixed starting point. So the other sample had to be what it had to be to match up. The only variable of adjustment to the matched gray was the poly percentage. Someone said the poly sheen was noticeable in some of the pictures so maybe Todd had taken that to the max then, I didn't see it but I'm not sure what to look for. I do know excessive sheen is distracting in much the same way excessive metallic sparkles.

I have said for a while that I believe having the surface being RGB neutral is very important I think it's even more important the gray level be selected properly. I can easily live with a slightly off neutral and calibrate to that and that then becomes a fixed constant in my setup. Brightness is not a fixed constant and the screens gray level has to be found that will allow for periodic calibration from new bulb to bulb failure. The lumens may very over the life of the bulb 50%.

The first thing to go when there is not enough brightness is surprisingly the dark detail. That seems odd at first thought because darks take the least amount of light to produce. But dark detail involves more than dark it involves CR to make the detail and that involves light. There is always going to be the spread between the best the projector can do when trying to send out nothing (black) but there is that something makes it thru. And when it tries to send out everything (white). The number of times brighter white is than black is the total CR of the system. But in a dark image the CR of that image is greatly less. That image of the tree in the details might have a CR of 5 or 10 is all. Because most projectors don't have a method to adjust CR on the fly, like the variable iris projectors and even they have short comings unless the whole image is dark detail. It's very important to stay in the sweet spot of brightness. You will never do better in terms of CR than the projector, room and screen will allow. But varying any of the 3 outside their best will diminish CR.

Gray screens don't improve CR but they can help to maintain it.

As usual, I agree with most of your comments, but I'm thinking that as the bulb ages and loses output, the full off light leakage may be reduced by the same percentage as the whites. This would actually produce deeper blacks and dimmer whites as the bulb ages. I noticed on my projector that when using economy mode vs high mode, the blank screen brightness changed considerably. So perhaps the contrast ratio of the projector remains about the same as the bulb ages.

Last night I swapped screens, and compared my latest dark gray with sheen screen with one of my older screens with a poly/pearl topcoat on a lighter shade screen. I recalibrated the projector with a DVE disc. I made some changes to the grayscale to offset some red push etc, and then watched the demo pictures on the disc. I also watched TV afterward. The screens are night and day different in shade. Both perform well enough that I could be happy with either. However the strengths of the dark shade are more to my liking than the strengths of the lighter shade. This comparison was made without ambient light in a pretty good room. Selecting a good shade of gray is easy. Selecting the best might take trying several to see what your preferences really are, and what you can get away with.

Will somebody step on the creepy crawly already?

This is almost a Phobia!

kbgl

I think we are pretty much saying the same thing and you may have taken or I may have worded my statement slightly wrong.

Yes as the bulb dims the ambient light in the room from sources other than the screen will remain the same and the screen remains the same.

My point is if you are of the opinion that some of are that an ultimate shade of gray and also an ultimate sheen level can be selected for a given setup there is only one draw back. That being if the selection was to be made around the new bulb brightness then you could have a screen that would become less than ultimate at some point in the life of the bulb. That's why I have cautioned people from going to the darkest of grays in the beginning even though the results at that point in time are better than something lighter.

If a screen isn't spot on neutral you can adjust for that and that won't change much from then on. Brightness has to be looked at as the biggest variable of change. Most bulbs take a hit after a few hundred hours and then hold pretty good for a long time. I kind of charted my brightness settings over time and at 200 hours I made a fairly good adjustment, each 200 hours after that the changes were small but always one or two clicks. After doing each adjustment the image was exactly the same as the first time.

In these last experiments Todd did the BW started out stressing the light limits he had, and you would expect the strain of those limits showed most in the darkest of images.

You are right as the brightness diminishes with a bulb the white end and the black end both come down together. Do they come down equally? I would think they would. Not really different than a projector with an iris to adjust or one with a ND filter.

There is no variable ND screen surface yet, one that would get lighter as the image gets darker to always allow the best shadow detail possible. That's why we need a screen that's been selected such that the projectors brightness can always be adjusted to give us the full gray scale range between white and black.

I always tell people if you only do one calibration do the one that sets the range from black to white. The rest can be done with filters or by eye to taste and most people will be happy.

One last point (at least in this post) on gray scale selection. Conventional wisdom recommends gray screens for ambient light. I have never believed that and I see reason for using them under mixed lighting conditions, as I do in my viewing room. If you wish a screen to be used under 2 or more ambient levels of light then the gray should be selected around the highest ambient light you have and then compared under lights out conditions and also recalibrated. Just so you know going in the overall brightness will drop as a bulb ages and you will be able to maintain the PQ over the life of the bulb with both ambient levels. What I have found is if you have the lumens and the dark screen to work with the ambient if anything you might be too bright lights out. And that has as much to do with our eyes as anything.



MM

Oh there ain't no bugs on me
There ain't no bugs on me
There may be bugs on some of you mugs
But there ain't no bugs on me

I think someone stole MississippiMan's identity. This post is way too short to actually be him.

I like using the whole screen to judge the overall effect. I've painted several 4 x 8 hardboard screens on both sides. If I get a good one without roller marks, I try not to repaint it unless I have already made a better one to replace it.

No I think he text messaged that post in from his cell phone at the same time he was spraying a hybrid BW clone screen. With his free hand I might add.

The post was quite short though I hope he hasn't ran out of words yet.

Hey, I think I'm insulted!