Question about screen type

[Ryan Gallagher]

So I spoke with MDI and we figured out that I have a northview screen with a 1.8 gain. They said that is too much again for my projector the NC1200C with the 2000watt bulb. I guess it’s reflecting too much light which is then causing me to be able to see the screen through the movie? I’m trying to learn what gain is on the Internet right now to try to understand better. He recommended either 1.0 or 1.3 gain based on my projector and the distance from the projector to the screen. He said it should not feel sticky and may have melted slightly under high heat in the theater maybe said that it’s probably due for swapping out. Can’t wait to find out the pricing of a new screen ?! Thanks again for everyone’s help I am getting a lot of value out of this group and am learning a lot about my theater.

Yeah 1.8 is considered a "high gain" screen (ie very reflective) surface. If it is actually sticky and not just shiny then yeah, something materially is starting to go. Other than heat like MDI suggested, if your room was ever a smoking permitted space, nicotine can actually break down a lot of those plastics and cause them to get sticky too. The other suggestion of perhaps someone having cleaned it improperly is also a possibility.

When you say "see the screen", are you meaning you see variations across the field caused by the screen, or are you actually seeing a brightness hotspot that moves relative to your location? (as Paul suggested). The former would indicate some kind of coating damage or uneven dust deposition, the other is just the normal behavior of high gain screens.

Personally, if it's not actually degrading (sticky) or damaged due to cleaning attempts, I'd wait and bundle your screen swap with a larger upgrade when you decide to move that room 4K. Xenon vs Laser will inform which screen fabric to invest in during the upgrade. There is also the factor that I wouldn't put a 15x21' screen back in unless you have motorized masking. I would lean towards a one of the standard scope or flat ratio screens, which may entail replacing more than just the fabric and add to the cost.

In the mean time you might want to actually meter your reflected brightness... maybe running the 1200C at something below full lamp power is actually better to hit the 14fL DCI spec?

I'd just hate to see you throw a bunch of money at an odd-sized screen for your existing 2K xenon, only to find out a couple years later you should have gotten a different screen fabric for 4K Laser.

[Mike Reed]

I'd just hate to see you throw a bunch of money at an odd-sized screen for your existing 2K xenon, only to find out a couple years later you should have gotten a different screen fabric for 4K Laser.

Thanks for the fast reply, I know the screen has been up there for just over nine years. It was replaced in October 2015. The theater has not been smoked in since the 90s. I didn’t realize 15 x 21 is an abnormal size for a theater. I don’t know the exact size of my other theater but I know it’s wider but the same height I believe. I don’t know if I can do more wide on the small side theater? Just the way the theater is set up right now. I know there is a jump to laser at some point in my future just don’t know when. MDI Said they can retrofit these NC unit units for laser which can save some money I guess.

As far as brightness goes there are no hotspots on the screen. All I can explain is it seems like you can see the screen sometimes through the movie. I only know how to adjust brightness on these NEC projectors with those XYZ access Allen wrench turn screws. Last I had was a peakhold of about 700 on that NC1200. When I first put in the new bulb in it in February it was around high 300s. I kept thinking it was not as bright as it should be So I’ve been able to get it up to about 700.

You are right about the screen and projector I don’t want to waste money I don’t have too.

[Ryan Gallagher]

Thanks for the fast reply, I know the screen has been up there for just over nine years. It was replaced in October 2015. The theater has not been smoked in since the 90s. I didn’t realize 15 x 21 is an abnormal size for a theater. I don’t know the exact size of my other theater but I know it’s wider but the same height I believe. I don’t know if I can do more wide on the small side theater? Just the way the theater is set up right now. I know there is a jump to laser at some point in my future just don’t know when. MDI Said they can retrofit these NC unit units for laser which can save some money I guess.

As far as brightness goes there are no hotspots on the screen. All I can explain is it seems like you can see the screen sometimes through the movie. I only know how to adjust brightness on these NEC projectors with those XYZ access Allen wrench turn screws. Last I had was a peakhold of about 700 on that NC1200. When I first put in the new bulb in it in February it was around high 300s. I kept thinking it was not as bright as it should be So I’ve been able to get it up to about 700.

You are right about the screen and projector I don’t want to waste money I don’t have too.

If you could find a test pattern or a trailer where you notice the effect, maybe a video would convey what you are seeing.

[Ioannis Syrogiannis]

As far as brightness goes there are no hotspots on the screen. All I can explain is it seems like you can see the screen sometimes through the movie. I only know how to adjust brightness on these NEC projectors with those XYZ access Allen wrench turn screws. Last I had was a peakhold of about 700 on that NC1200. When I first put in the new bulb in it in February it was around high 300s. I kept thinking it was not as bright as it should be So I’ve been able to get it up to about 700.

When changing the lamp, you need to focus the lamp to its highest output by using the three knobs for each axis of the three (X, Y, Z). If not, you may have great heat losses and higher than necessary temperatures.
The brightness of the lamp (and wattage) is set in a certain setting of the DCC, that you can have different, depending on whether you have a Flat or Scope preset.
What is the proper value, is a matter of setting in compliance with the measured output. A technician should have a meter with their tools, if asked to carry, but there are a couple for xenon lamps that are not nearly as expensive as colorimeters or spectroradiometers are.
What I want to rely: You focus the lamp as best you can through the Allen keys, after 10-15 minutes of having the lamp on and screening white test pattern.
You set the brightness through the DCC program and save the proper setting for Flat, Scope, or other.
There might be special occasions where you might need to get the lamp slightly out of focus (mostly by defocusing with the Z knob), but that is very rare and I wouldn't bother giving much thought to it, unless you can't bring the brightness down to proper levels through wattage.

[Stefan Scholz]

In my view, screens are due for replacement after 8, max 10 years. The base material degrades, coatings degrade,
softeners vanish, and what once was a white surface slowly becomes yellowish or brownish.
Screens are not really expensive, as long as you don't insist on one of those newer high tech 3 D surfaces, they offer
with benefits. These are costly. Matte white in standard digital perf (meaning unevenly distributed punched holes to avoid moire) is
pretty reasonable. Often the cost of shipping as a roll as special freight is higher than the screen price.