Gain Readings

**mechman** · **02-23-09, 02:27 PM**

For now all of the gain readings are posted here. They will all be here soon though.

Well I had a big long write up of how I obtained all of the readings and what not and I accidentally hit a button on my favorites toolbar and lost it all. For now I'm going to do a brief synopsis and I'll add more later.

Four sets of readings were taken of seven of the samples and the rest had two sets done. The two sets for all of the samples were done using a halogen worklight that has outputs of 250, 500, 750 and 1000 watts. the two readings were done at 250 (pretty much the same as a pj bulb) and at 1000 watts. The seven samples that had more readings had these original readings confirmed by my pj in my theater room. All readings were taken using a Sekonic Digital Master L758C spotmeter.

The optimal position was determined by what angle and height the meter had to be set up as well as which portion of the material gave the highest reading. This was a fairly easy task for the majority of the materials. But for the High Power and the Pearlescent it was a bit more difficult.

The data was entered into a spreadsheet created by Jim (cynical2) and customized by custard. It factored in a three point average which is explained quite nicely by Jim:

Quote:

I have a few comments.

* Overall, the data looks very good. Consistent, intuitive, no "showstopper" surprises.
* I assume from the data that we can get only 2 digits out of the measuring device. The rounding causes some small discontinuities in the data. You can see an example in the blue line on the chart below that I made for "Black Widow N=7.5". The bump is caused by a drop in the MgCO3 baseline from 15 to 14 (in reality, it may have dropped 14.5 to 14.4, which would have eliminated the bump...but since it rounds to 2 digits, we see the unexpected discontinuity).
* Applying a smoothing algorithm really helps the data in those instances. The maroon line in the plot shows a 3-point moving average applied to the raw data. When using a technique like this, it makes sense to preserve the 0-degree point and the 2 endpoints...otherwise they'll be falsely effected.
* Another question that came to mind...when we discussed the "theory" behind measuring gain, I thought that MgCO3 was supposed to have the same gain from any angle. In reality, we're seeing it fall off (not much, but a bit) as we get to extreme angles. Anyways, for the of it, I created the green line below. This line measures gain while assuming that the baseline never changes. In other words, it uses the 0-degree MgCO3 reading to calculate the gain at all angles.

Between the 2 techniques that I tried, I think that the smoothing algorithm makes more sense. Taking a baseline reading at each angle and then comparing to the screen reading seems like the right way to go, as it removes any impact of the test environment, measurement setup, etc. However, if we have 2 digits to work with, the smoothing algorithm should help take care of anomalies we see from rounding error.

So, I'm recommending that we smooth the raw data rather than use it directly. If you guys are in agreement, I will combine all of the readings into one spreadsheet, and create a template into which data can be entered as new screen materials are added.

There are 3 charts per setup, so the seven that I took 4 separate readings for will have 12 charts.

**mechman** · **02-23-09, 02:29 PM**

Black Widow Gain Readings

**mechman** · **02-23-09, 02:30 PM**

Silver Fire Gain Readings

**mechman** · **02-23-09, 02:31 PM**

S-I-L-V-E-R Gain Readings

**mechman** · **02-23-09, 02:31 PM**

Valspar Ultra Premium Flat Enamel Winter Mist

**mechman** · **02-23-09, 02:32 PM**

Valspar Ultra Premium Flat Enamel Veil

**mechman** · **02-23-09, 02:32 PM**

Parkland Polywall

**mechman** · **02-23-09, 02:34 PM**

Da-Lite High Power

**mechman** · **02-23-09, 02:34 PM**

Da-Lite Da-Mat

**mechman** · **02-23-09, 02:35 PM**

Da-Lite Cinema Vison

**mechman** · **02-23-09, 02:35 PM**

Da-Lite Pearlescent

**mechman** · **02-23-09, 02:35 PM**

Carada Brilliant White

**mechman** · **02-23-09, 02:36 PM**

Elite CineWhite

**mechman** · **02-23-09, 02:37 PM**

Wilsonart Designer White

**mechman** · **02-23-09, 02:37 PM**

All the charts have been posted and if you want to see the numbers (we're still working on a proper format for them here in the thread) they're at this web page.


		When I refer to the gain readings I will be rounding them to the nearest tenth. I have never seen any readings that were listed to the one hundredth.

The Da-Lite samples measured pretty much as the manufacturer advertises. The High Power measured at 2.7 with a 25-30 degree viewing cone. Da-Lite states a 2.8 gain with a 30 degree cone. The Da-Mat material measured 1.0 across the board for the most part. This is advertised as a 1.0 gain material with a 60 degree cone. The Cinema Vision gave me readings of 1.1-1.2 gain with roughly a 45 degree cone. Da-Lite has this listed at 1.3 and 45 degrees. Pearlescent gave readings of 1.4-1.5 for gain with a cone of 45 degrees. This material is listed at 1.5 and 45 degrees.

The Elite material I used was a 30" square sample of their CineWhite. Elite has the gain for this material listed at 1.1 and my measurements were 1.0-1.1, depending upon the light used. They list a viewing angle of 80 degrees and my measurements confirm this.

The Carada material was a sample of their Brilliant White. Carada lists it's gain at 1.4 and both of my measurements were 1.3. Carada doesn't list a viewing cone or angle and I didn't show any from my measurements.

Now onto the diy materials/paints! Parkland Polywall showed a gain of 1.0 and no viewing cone issues whatsoever. The gain for this is a bit confusing for me as I thought it would be more in the .9 range as it's luminance reading was 93.4. I guess there's a touch of specular gain to Polywall.

Designer White once again proved it's worth as the best diy white screen out there. It posted a gain of 1.3 in both tests and the viewing cone was greater than 75 degrees.

The Winter Mist sample used was a Valspar Ultra Premium Flat Enamel. It's gain was consistent with respect to both light sources. .9 gain is respectable for a plain jane neutral gray!

Again, absolutely no viewing cone.

Veil was a neutral gray tint that was called a Black Widow equal when purchased as an exterior paint. We disproved that here. And we most definitely do not recommend exterior paints inside a house! Anyways, I bought this paint because of it's similarity on the neutral scale to BW. It was another Valspar Ultra Premium Flat Enamel brand. It's gain was .8 (BW is .9). And as has been the case, this paint shows no viewing cone problems.

This leaves the three advanced paint mixes. Two of which are extremely difficult to mix and apply and one is extremely easy - Black Widow is the easy one!

Silver Fire - the list of things that can go wrong with this mix is long. It also uses an incredibly high amount of mica and polyurethane which causes hot spots. My Mitsubishi HC3000U could not adjust out the hot spots without sacrificing some other picture quality with this mix. ***note*** all of the gain tests were done with the exact same light as the rest. When I say 'adjust' I'm talking of a previous test I'd done with this panel. *** This is also the mix that I received two samples from two completely different individuals in two different parts of the country and all three of them had the same identical spectral curve - very wavy. The funny part is that none of the three looked the same. All three were very different by eye with one clearly showing a sparklie finish from the massive amount of mica.

Silver Fire is a concoction done by the 'artists eye'. An interesting note to this is that artistry uses a completely different color space than movies and video. One of the boisterous authors of this mix claims that it has a gain of 1.25 to 1.4 (I've seen him state them all). Well he's a bit off. The gain of Silver Fire is 1.0. And it's viewing cone is 30 degrees. The tight viewing cone is more than likely due to the amount of polyurethane and mica in the mix. It's a 64 ounce mix comprised of only 10 oz of real paint.

It should be noted that Silver Fire has changed it's formula for the fourth (??) time since these mixes were done. Some day I may do it again but it's doubtful that it's worth the hassle

S-I-L-V-E-R is another complicated mix that changes over time. It consists of a Kilz undercoat with successive layers of mica and faux glaze. Unlike Silver Fire, I could actually get my pj to adjust properly for this mix. Yet to tame the hot spots I needed to turn the brightness way down. Silver has a gain of 1.3-1.4 and a viewing cone of 30-45 degrees. Here are some shots of S-I-L-V-E-R and Silver Fire hot spotting:

Silver Fire is the bluish purplish looking screen.

Black Widow - BW gave results that we were expecting. A part of us really wanted it to be around 1.0, but we knew it wasn't likely. Gain of .9 and absolutely no viewing cone issues to speak of

**mechman** · **02-24-09, 12:37 PM**

I sprained my right thumb pretty badly last night playing hockey. Thought I broke it but the x-rays were negative. I'm going to open up the thread but I'm not going to do much to it for a day or two as it's a bit painful to type.

**mechman** · **02-26-09, 01:21 PM**

The web page I created has now been updated for easier navigation. All of the samples are listed along the bottom. When you click on a sample you get the numbers followed by all of the charts.

Gain Readings Web Page

**mechman** · **02-26-09, 05:02 PM**

Conclusions posted.

I think another interesting thing to add is that there are probably thousands using Black Widow at this time. At one point in time, MississippMan had pleaded with others to show their Silver Fire shots off. No one responded. We've never had to beg anyone to show off any shots of Black Widow. Another interesting thing, the BW thread is one of the most highest viewed here and at the other forum. It easily outdistanced the other two in a very short period of time.

**wbassett** · **02-26-09, 10:16 PM**

Great job mech.

On the white side of things Designer White is still holding up to it's reigning claims as one of the best white screens around be it commercial or DIY.

How small of a sample can you measure? Can we get any readings off the sample chips of Fashion Grey, Platinum and if possible maybe some of the box of samples I sent you a year or so ago. One of the samples is of Digital Image's commercial screen paint. Some gain readings and color balance specs on that would be interesting if possible.

Once the weather breaks I'll see about finally getting a quart of Black Jack out to you. It would also be interesting to see what the gain is on the aluminum by itself.

**texfrazer** · **02-27-09, 12:18 PM**

WOW!

Mechman, you continue to amaze me with all of the incredible amount of hard work and skill that you have brought to the projector screen forum. If you are ever in the Knoxville area, please let me know cause I've got a beverage of your choice with your name on it.

I'm going to need to put up a plaque on the wall of my HT that is dedicated to the Shack, with special thanks to you, Bill and Wayne.

**mechman** · **02-27-09, 02:26 PM**

Quote:

wbassett wrote:

How small of a sample can you measure? Can we get any readings off the sample chips of Fashion Grey, Platinum and if possible maybe some of the box of samples I sent you a year or so ago. One of the samples is of Digital Image's commercial screen paint. Some gain readings and color balance specs on that would be interesting if possible.

Once the weather breaks I'll see about finally getting a quart of Black Jack out to you. It would also be interesting to see what the gain is on the aluminum by itself.

The measured area is quite small considering the 1 degree spot meter. However, I need a rather large sample to find the brightest location. Working with the small Carada sample (something like 8X10") proved to be a test of my wits. So I'd say at least a 2' square sample at a minimum. And that leaves out the sample chits.

It really seems like the plate is gonna be full here for awhile. As soon as I come back from the 5 day hiatus next week I would like to get concrete evidence of translucency done first. And then it seems like Elite has some more work for me as well.

Not to mention the mirror theories to go with translucency...

**mechman** · **02-27-09, 02:27 PM**

Quote:

texfrazer wrote:

WOW!

Mechman, you continue to amaze me with all of the incredible amount of hard work and skill that you have brought to the projector screen forum. If you are ever in the Knoxville area, please let me know cause I've got a beverage of your choice with your name on it.

I'm going to need to put up a plaque on the wall of my HT that is dedicated to the Shack, with special thanks to you, Bill and Wayne.

We do aim to please!

**custard** · **02-28-09, 05:40 AM**

gain tables added to compliment gain charts.

**robert_1967** · **03-02-09, 03:19 AM**

Really mech, it is so refreshing to see someone actually have some facts behind the discussions. HTS is the most reliable source of intel on screens and their performance imo.

Aboslutelly great work !

**Quantum** · **03-02-09, 08:11 AM**

I've been waiting and hoping to find C&S...

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