HTS-X2 - an experimental N8 reflective screen mix

I mixed up the paints and used about 2 fl oz of distilled water to rinse out the various containers. It was still pretty thick looking but rolled nicely. I used the Tiddler single roller method completing each "stripe" with a gentle downroll, overlapping the previous by half a roller.

My first coat scared me because after it had dried for a couple of hours, it was "blotchy" (there was a speckled effect of dark and light, pretty consistently across the screen as if some parts dried thicker and other parts dried thinner). I rolled the second coat at about two hours and after an hour it looked tons better. I decided to roll a third coat since I had the paint to spare.

After the third coat had dried for about 90 minutes I could not resist and fired up the PJ. Without it fully curing and without a greyscale recalibration, it still looked pretty good to my eye! Blacks were definitely better and white still looked good. I watched a few minutes of Bolt, there's a scene where Bolt (white furry dog) and Mittens (black furry cat) are wrestling around and the detail in both the black fur and white fur was pretty good. I also checked out my standard test movie, the Fifth Element and it looked superb. So first impressions are high!

I took a bunch of photos of the process that I'll post here later. I will also try to take some "good" shots of the screen once it has cured (and I learn how to use the white balance feature on my camera...)

Here's some pics.

Supplies all laid out:


Two quarts. One is the base for C&S one is the N6 paint Harp came up with.


The C&S base before mixing in the Craft Silver Metallic:


HTS-X2 mix in the can:


HTS-X2 again:


Ready to roll:


The next three shots are the screen (124" diagonal) after rolling three coats of HTS-X2 and a 28 hour cure.

All the lights on, camera flash on:


Partial lights on:


Lights off, just the flash:


I don't really see a difference between the three shots, I guess that's cos the flash fired off for all three. Should I try a shot with the lights all on and no flash? I am not much of a photographer beyond pressing the button on a decent point and shoot, but if there's any particular shots you want to see, let me know and I'll take them. Harp suggested taking a screen shot after calibrating the white balance to a white screen from a calibration disk. I'll try and grab that and any others you want to see tomorrow night after the paint has cured for a full 48 hours.

Hi,

I've been a bit tardy about calibrating my PJ after applying the HTS-X2, but today I finally found time to lie on the floor for two hours running through a calibration.

My PJ is an Epson 6500UB with only ~75 hours on the bulb. I only have a Spyder3 colorimeter, so take the results with the appropriate pinch of salt given the gear I have. I used HCFR and followed the procedures in a thread I found on AVS using the 75% Saturation windows. Gamma was a bit of a pain in the bum, but I think the results look good.

Attach is the CHC file (zipped) from HCFR showing the post calibration grayscale results. I am not an expert and don't really know if the attached results are anything to be happy with, but my eye says it looks good.

I plan to take some screenies (hopefully tonight) and will set the white balance of my camera to a 100% White screen from the calibration disk I used (AVSHD709) before taking the shots.

Here's some screen shots. All are from MKV files on my Popcorn Hour as opposed bluray originals. My camera is a Canon G9. I had it mounted on a tripod about 17 feet back zoomed in. Lights were all off. I first did a custom white balance against a 100% white screen from the AVSHD disc.

Fifth Element (1080p) (I was a little too zoomed in for this one). The third shot looks a little "edgy" but it doesn't look so bad i real life:





Bolt (1080p). The fur details are pretty good in this movie:





Finding Nemo (720p)

Harpmaker said:

Very nice indeed! I'm still blown away by them. :unbelievable:

Click to expand...

Well the thanks goes to you... you gave me the formula. I just did the grunt work.

Harpmaker said:

A major component in these photos is that the PJ was calibrated to the screen (which is D65 neutral) and the camera was white balanced to the screen with a white image being projected.

Click to expand...

The pictures came out better than any other's I have taken, which never seem to do the real world experience justice, I think the white balance idea was the clincher. I would say they are pretty close to what I see with my naked eye. Nemo, especially, looks superb.

Harpmaker said:

The reason, IIRC, that 1C2 went with the N8 screen was to improve image contrast and black levels over his white screen. I would say it worked! :bigsmile:

Click to expand...

This was indeed the reason. I had two goals.
1. For relatively little investment, get a screen that would perform as well as, if not better than, something I'd have to spend $1K+ to achieve if buying a "real" screen. I feel this is achieved. The results have more than exceeded my expectations.
2. Be able to handle a little ambient light for when we play Wii and still have the colours look decent.

custard said:

the measurements you have taken are with the colorimeter pointing at the screen.

what Mech has asked for is for a second set of measurements with the colorimeter pointing directly at the PJ. the second set is used as a baseline measurement and helps us see if the screen is causing a color push.

i have an i1 display and it freezes when taking direct readings from the screen. hopefully you dont have the same problem.

Click to expand...

Thanks custard. I PMed Mech for some specifics, so now I just need to do it. I am using a Spyder3, so we'll see how it goes. A couple of times when doing 0 IRE readings for the grayscale, the Spyder and/or HCFR froze up, it doesn't do well in low light, but I have never tried blasting it with the light directly from the PJ.

Sorry for the tardiness. I was off work today so carved out some time to do the readings Mech requested. Hopefully done correctly!

In the attached zip file should be two files:
ProjReadings.chc - HCFR readings for Greyscale, Primaries and Secondaries with the Spyder3 roughly halfway up the screen, about 5 inches from the screen, angled toward the projector lens. (I took realtime readings and fiddled with the angle to tweak the highest ftL)

ScreenReadings.chc - HCFR readings for Greyscale, Primaries and Secondaries with the Spyder3 just below halfway up the screen, about 12 inches from the screen, angled toward the halfway point of the screen. (I took realtime readings and fiddled with the angle to tweak the highest ftL)

I don't really know what I am looking it in truly analyzing these files, so I'd appreciate some "here's what you discovered" type summary after you've analyzed them, if only for my own learnin'.

mechman said:

Basically, all we're doing is comparing the two. The readings from the pj is what is hitting your screen. And the reading from the screen is what is reflected back. If there's a difference between the two, the screen is affecting the image. If it's a big difference, as I've seen with some things, it may be detrimental to the effect of not being a viable solution.

Click to expand...

This part makes sense. Using computer numbers, if I shoot a 255,128,0 and get back a 249,128,0 then the surface I am shooting on is "absorbing" 6 points of red and is thus not completely neutral.

My original question is more understanding the significance of the various graphs available in HCFR.

mechman said:

My initial look at the numbers shows me very little difference between the two readings. I see a very slight drop in blue, but nothing significant. Looks good so far! :T

Click to expand...

Good example, in one of the graphs I did see a difference in the blue line from the two different sets of readings.

mechman said:

Also, I disregard all of the readings below 30IRE. I'll have more for you later this evening when I have a bit more time to look at these files. :nerd:

Click to expand...

Good, cos I notice the numbers are all over the place at lower IRE. Is that that simply because the Spyder3 is not good at low IRE? I assume the super-spendy colorimeters do better at low light.

Slightly OT: Generally speaking, total neutrality is the ideal goal, but also exceedingly difficult to get perfect. So how big a deal is it? Is not the purpose of a calibration to correct for such differences? I understand a big push in one colour may be too big to correct for, but little ones should be no big deal. Could you actually have a screen surface that is a better overall performer in other respects but exhibits push in one colour. A good calibration can correct for the push, leaving you with a better screen than one that was perfectly neutral but less well performing in other respects?

I understand as screen formula developers that the holy grail is totally neutral, but is there a risk that goal is followed to the detriment of other goals? For example, on other forums it seems that gain or reflectivity is the goal, to the detriment of neutrality. I'm not claiming to understand the complexities of the art/science, just curious...

Wow! Detailed explanations guys. I warned you I was ignorant to the complexities of the issues at hand. I knew the gain crazy folks were off the mark, more because they didn't seem to care about other factors that would seem as important, if not more. As I said before, that's how I found my way over here from AVS.

I am certainly extremely happy with the results of my screen. I am guilty of buying a PJ without considering my room first, but also think I have ended up with an apporpriate PJ all the same since I have good light control and a powerful PJ (Epson 6500UB). Thankfully it also has a good CMS, so I have been able to tweak out any potential non-neutral quirks from HTS-X2, but the final verdict on that is now down to Mech. Whatever your results, I don't fele compelled to change anything as the screne more than meets my expectations. So unless you have some numbers that show me something is way out of wack, I'll consider myself done.

BTW, I forgot to mention, my PJ bulb only has 90 hours on it. As bulbs age, do they typically change their colour representation, or just get dimmer?

Thanks again. I am looking forward to Mech's assessment.

Harpmaker said:

Sorry about that, I have an embarrassing tendency to let my inbox get full. :blush:

Yes, I got your sample and it looks great! Below is the Spectral Reflectance Chart for it. The bump in the deep violet and orange, and the dip in the extreme red end of the spectrum are indicative of a very neutral mix. We still don't know why neutrals have this curve. :dontknow:

The L* value equates to a N value of 7.84, which is a tad under the 8.0 value of a true N8, but only the most discerning eye could tell the difference even in side-by-side testing. The a* and b* values are both well under 1.0 and the fact that they are opposites (one negative and the other positive) is also very good.

The color temperature of this mix is 6487°K which is only 16° off from the D65 standard of 6503°K.

Well done! :clap:

Click to expand...

Well, I think the "well done" needs to go to you, since you provided the formula, I just followed the steps...

The colour temp is only ~0.25% off, I'd say that's a pretty small margin considering how simple the formula is (three ingredients). So if the goal is simplicity with consistent results, that's very impressive!

The N value as well is a pretty small margin (2%), so all things considered an impressive result (and a lower N is probably okay for me anyway since I have good light control and a powerful PJ lumens-wise).

Not sure if I told you, but the sample card was rolled at the same time as the screen. I did coat 1 on the screen, then rolled the card. Waited. Then coat 2 on the screen, rolled the card. Waited. Then coat 3 and rolled the card. So its pretty representative of what went up on my wall. The only diff is the card was not primed with Kilz2, but it was a white card from a frozen food box. Given I put three coats on, I'd guess the primer (or lack thereof) would make a minimal difference.

As I've said before, I am exceedingly happy with the results, but its nice to have some science to back-up my satisfaction.

As per Mech's post, I have a little more calibration work to do - which I'll hopefully get to this weekend - its just nice to know I am calibrating against something that's pretty much ideal for my needs.

Thanks again guys!

Harpmaker said:

In the mix family that HTS-X2 will be a part of the range of gray shades will be determined by how much neutral gray paint is added to regular C&S. In theory this would be an "infinitely adjustable" mix with any value from C&S alone (N9) down to where the gray paint comprises too much of the mix and the reflective properties of C&S are visibly diminished. In the real world this infinite adjustability is more about marketing hype than truly useful. Through testing and observation we have determined that there isn't much sense in having mixes closer together than N0.5 which is a "half-N" step.

Click to expand...

Well I certainly think the idea is a great one. It was very easy to mix - the addition of the N6 to darken an already tried and tested formula is a bit of a stroke of genius if you ask me.
Theoretical question: how would BW compare to C&S plus enough N6 to be as dark as BW? Could it be better, or is it expected to be worse?
Next theoretical question: could a "lightener" be added to BW to achieve similar results?
Last question: Would this formula replace Scorpion? Its certainly easier to make (which is why I got here), it seems neutral enough, but is Scorpion "better"?

Harpmaker said:

I forgot to comment on this before, but if your screen surface is the same as the sample card you would have gained little, or nothing, by spraying instead of rolling! That sample is the smoothest rolled sample I have ever seen. :T

Click to expand...

Well thank you The only trick I can share is that I am pretty . I have done a fair amount of rolling for house decorating, so I have a bit of experience, but this was still a slightly new challenge, but probably only because I was more obsessive about it.

In the end I didn't really do anything different than when rolling a regular wall, other than probably go a little slower and be conscious about applying even pressure to the roller, etc... I followed the Tiddler technique, but then that wasn't too far from how I roll a wall anyway (other than doing the old W trick first). When I look at my screen up close, I cannot see any obvious lap marks or inconsistencies which is the thing I was most fearful of. I will say that the third coat probably helped with this so I feel its worth doing a third coat if you are rolling.

Hoping to do a second round of calibration today, but then I just bought an Xbox 360 for the HT room, so we'll see what wins...

I went from a white Kilz2 screen (124" diag) to the N8 formula here and there were no negatives whatsoever from my perspective. Its not a super dark screen surface (its actually quite an attractive colour) and the image projected is plenty bright.

When I first started looking at DIY formulas, I was leaning towards an N8.5 or N9, partly out of fear that N8 would be too dark. I concluded that I was "wimping" out and should probably just stick with white if that was my fear.

If you do a calibration on your PJ after painting the screen, I am confident that you will be happy with the results at an N8 based on your PJ specs. I can honestly find no negative that I feel is a trade-off for the positive. My blacks are blacker and my whites still seem white (check out my Bolt screen shots). The colours are very rich (check out my Nemo screen shot). If you want to see more pics of my theatre, check out my PhotoBucket album. From page 3 there are shots of my colour scheme, you can see I have a white ceiling and reasonably light brown on the other walls, I just painted my screen wall a dark chocolate brown.

We also play Wii/Xbox with the wall sconces on but dimmed, and the image still looks excellent. Providing you have good ambient light control for daylight especially, I don't think you'll regret going N8. Some folks who went N8 later go N7... I am not a professional by any stretch, but my eye tells me I made the right decision.