[mechman]

Robert,

Just a quick note. I'm gonna have to digest what you're saying here and get back to you after church. I may need a bit of clarification as well. Expect more later. :T

mech

 

[mechman]

Mech. Your GAIN tests made me sleepless....ok, that would be stretching it, but it made me think.

As I understand it a GAIN curve is the relative value of amount of reflected light from various angles in relation to a known ref sample of Magnesium Carbonate. So if I measure the ref sample two times and calculate the resulting GAIN I would get a 1.0 from 0-180 degrees, right? (I know, futile example but I am trying to make a point here, bare with me).

Correct

Now, lets try to do a new GAIN measurement, but with a perfect gray, say of N9. In my world that would then result in a somewhat lower value, perhaps 0,95 (just an arbitrary figure), but it would be completely flat across 0-180 degrees. From a reflected ENERGY point of view, then we could say that the total amount of reflected energy is lower compared to the ref sample. From a math point of view, the area under the curve (the integral from -90 to +90) is less that the ref sample.

Correct. Look at Black Widow.

Now lets try to look at your measurements.

Silver Fire. It peaks at zero degrees just a hair above 1.0 and falls drastically 0.5 at 30 deg. From an reflection point of view I would like to see that as a very bad screen. The relative amount of reflected light at its peak is virtually the same as the ref. And tons of light is "blocked" as soon you look from the side.

Silver Fire is a bad screen in my view. :yes: As for light being 'blocked' I'd say no. It's just not being reflected that way. It's an excellent example of "polyurethane gone wild" in my eyes! The polyurethane is more than likely ruining what little reflection it would pick up from the mica. And concentrating what little it can add to the on axis gain. Is that making sense? :scratch:

S-I-L-V-E-R. Now we are getting more total light(energy) back compared to Silver Fire, but still clearly less than the ref.

Oh I think I see what your trying to quantify now, the total light from all angles with reference to MgCO. I don't think that would be a good quantifier for a screen because it would be a total energy number and I'd guess 90% of theater users wouldn't care about that last 30% of light lost. But I think I see your point and I think it is something we could do. Maybe do something for 0-60degrees and wash out the last 30 degrees? We'd have to figure out which angled measurements to include. So if I'm following what you're saying, take the gain from each angle and divide by the number of measurements for a total energy equivalency. Is that right? Bud over at the other forum was a big energy guy. I never really thought it was necessary as the current standards explained things quite well in my mind. But I'm open to it! :T I would guess the highest number would be the standard (magnesium carbonate) and anything that lines up close to it would be good. And maybe we could have a 30 degree enrgy chart and a 60 degree energy chart - mainly because I think the High Power may be better served this way. :dontknow:

Thoughts:
1/ The Silver Fire might have superior ambient light properties. The GAIN chart works both ways. Light not coming straight in will be blocked. Right?

Nothing is ever blocked. It's either absorbed or reflected.

2/ Why is the totally reflected amount of energy not used as a "performance index" for a screen? RI=Reflection Index

Don't know. Are we gonna start something:? :bigsmile: I nominate you! You have the data. Now let's hash out a HTS standard.

3/ Is it possible, in theory, to get a screen that reflects MORE energy in total compared to the ref?

If one were to use a 30 degree energy value I'd guess the high power would. But that's without me looking at the numbers.

I definitely think this may warrant further discussion! Or I could very well be cuckoo... or both! :dizzy::coocoo::dumbcrazy:

 

[mechman]

Robert,

You may have to expand on your energy formula for both Harp and I. I was just playing around with the numbers and there's a couple of ways to do things. Let us know how you would calculate the energy based upon gain.

I'm still not sold on this because I think gain relates this. :dunno:

 

[mechman]

Robert,

I'm with harp on the pondering for awhile. :T I don't have enough time at the moment to digest this. Right now I'm a bit busy trying to keep you up late again tonight. Check the web page out again later. I'm adding all of the readings from the pj bulb at 100 and 70 IRE. Maybe you can take a nap right now? :rofl: :bigsmile:

I'd like to add that it does seem very intriguing! :T

 

[mechman]

Wow! This has developed into something way above my pay grade! :nerd: :dizzy:

 

[mechman]

I'll echo what harp said! :yes:

 

[mechman]

LOL .

But really, mech and of course all other out there, what do you think about the HTS suggestion?

GAIN X:Y:Z => X=Peak Gain at 0 degrees, Y=percieved acumulated reflected light from 0-30 degr, Z=percieved acumulated reflected light from 0-45 degr. (all figures related to the magnesium block)

RI => Reflective Index. Range from -1 to +1. -1 equals 100% retroreflective and +1 is a mirror. Zero is a ideal lambertian screen.

I think maybe Z should be 0-60 degrees. While a lot of folks have the long, narrow, straight room, some also have a long wide room. I have a fairly narrow room and I find myself sitting at 60 degrees quite often when guests are over.

Now, tell us non-engineers how we calculate Y and Z... in layman's terms!

 

[mechman]

Happy that you enjoy our artithmetics :bigsmile:

Basically, what you could do is 10 deg incremental measurements 0-60 deg if that is enough in your opinion.

Can we stick to every 15 degrees? I could do 10 but then I'd have to redo a bunch of stuff. And in all honesty, this stuff is extremely time consuming... :hide: :hissyfit:

 

[mechman]

Here's a MgCO spectrum chart for reference.