Question about screen type

[Mike Reed]

Hello,

I have a small 2 screen theater. We have a larger theater side (275 seats) and a smaller side (190 seats). The smaller theater has a 15' tall screen by 21' wide. From what I gather the screen is from MDI and is a Northview screen. At least that was on the label the shipping carton from 2015. I bought the theater exactly 1 year ago today. This MDI screen has a type of shiny coating on it that my other screen does not have. When you watch movies on this screen during some scenes you can see the screen through the movie. Not a great viewing experience for my customers, although few have said anything. It personally bothers me to see the shiny screen through the movie. This is not an issue on my larger screen as it does not have a sheen on the screen. Obviously I can get another screen but why would they make a shiny screen like this in the first place? Perhaps my projector is not bright enough on the screen which could mitigate this issue? Did the old theater owner order the wrong type of screen? Obviously still a newbie here Thanks!

[Ryan Gallagher]

Others will have more exact answers, non expert opinion:

If you can deduce the model of each screen, looking up the product specs for the "screen gain" value might illuminate your query. Various coatings are used to increase the reflectivity and "gain" of screens to boost perceived brightness. Way back in the day this was called "silvering", hence the expression "Silver Screen" that has entered cinema culture.

My understanding is they are not very compatible with modern laser projectors. They can also create perceived hot spots from the viewers perspective at the angle of incidence relative to the projector source.

The reasons for using such screens all had to do with increasing brightness, especially on large screens in long throw situations, to boost the brightness because going bigger with a lamp is not always practical. Also before xenon going "brighter" with a carbon arc was generally even more impractical. I would expect most carbon-arcs operated near the same brightness and it was a question of efficency of the optical path that was the main point of variability.

I would guess that perhaps your shinier screen dates from an older install. And the more matte one is a newer screen? Or simply they viewed the larger room as justifying the higher gain screen, but not the small one.

[Ryan Gallagher]

Also if any rooms are still 2K projectors, I wouldn't upgrade the screen separately from the projector. Get a screen that pairs well with the intended projector technology. Or at least know what direction you are headed with projector technology before doing a new screen if you have to do them out of sync for financial reasons.

That said the screen you have might be "fine" for your setup, and you are just paying enough attention now to notice the difference in coatings and gain behavior.

[Carsten Kurz]

What type of projector is installed for your smaller screen?

[Mike Reed]

What type of projector is installed for your smaller screen?

I have a NEC1200C projector with a 2000w LTI lamp. Replaced the lamp this past February.

[Mike Reed]

Hey Ryan thanks for the information. I do not have a laser projector, its an older one with the replacement bulbs NEC1200C. The newer screen is the smaller one. Im not sure the make of the other screen that shows a better picture.

[Steve Guttag]

There are different types of coatings on screens, particularly gain screens. Depending on manufacture and storage, they can definitely decompose and get this sticky like sheen on them. I have also seen screens get installed with the wrong side out (more than once). I believe MDI puts, at the bottom-center an indication of which side should be the front side or the back side. Often the back side is shinny.

15x21? 1.4:1? I hope that you never fill it in height, except, maybe, for classic titles. The NC1200, with a 2KW lamp it is going to struggle going above 7500 lumens With a new lamp, new reflectors, clean optics, running hard, it can hit 9000 lumens. But it is best to think of it as a 7500 lumen projector, if you want to hit your light levels. Also note, not all lamps are created equal. You can put in the same wattage from different manufacturers and get different lumen outputs and, as importantly, different decay rates (how fast does it drop from 9000 lumens to topping out at 7500 lumens).

[Mike Reed]

There are different types of coatings on screens, particularly gain screens. Depending on manufacture and storage, they can definitely decompose and get this sticky like sheen on them. I have also seen screens get installed with the wrong side out (more than once). I believe MDI puts, at the bottom-center an indication of which side should be the front side or the back side. Often the back side is shinny.

So I checked today and the front is shiny like I mentioned before but the back of the screen is matte white. I looked everywhere but did not see a marking on the bottom center indicating which side should be front. However this checks out that the screen was probably put on backwards

Its gonna be a pain to flip it but I think I want to because the viewing experience is below my standard. I have tried to make the brightness as high as possible. I appreciate the insight too!

[Ryan Gallagher]

So I checked today and the front is shiny like I mentioned before but the back of the screen is matte white. I looked everywhere but did not see a marking on the bottom center indicating which side should be front. However this checks out that the screen was probably put on backwards

Its gonna be a pain to flip it but I think I want to because the viewing experience is below my standard. I have tried to make the brightness as high as possible. I appreciate the insight too!

The thought it might be backwards was just a suggestion. I wouldn't jump on board that conclusion immediately, as it may be just the gain coating (or the degradation of the gain coating) that is creating the sheen on the front side. Just cause the back is matte white doesn't mean it was intended as a viable projection surface, although it "could" work, you might end up with a very "unknown" screen surface relative to intended.

If it is thermally welded along the edges to create a fold-back hem line... then you might be able to tell which was the intended front that way too. Typically they would fold away from the projector to create the double layer hem at the edges. I would also dig through any records available at the theatre, perhaps there are some receipts or invoices that would further clarify the fabric details and installation dates. If you know who the integrators were and they are still in business, they might have those records too.

[Mike Reed]

The thought it might be backwards was just a suggestion. I wouldn't jump on board that conclusion immediately, as it may be just the gain coating (or the degradation of the gain coating) that is creating the sheen on the front side.

I appreciate the suggestion. I know its more of a suggestion. I was thinking of calling MDI and asking them about it. I wasnt going to hastily flip the screen. Just trying to better understand why the screen seems off. Could be the degradation of the screen too like you mentioned. All I have from the theater is that shipping label from MDI with a little information about the screen. I think the previous theater owner installed himself.

[Randy Stankey]

On all the screens I have installed, there has always been a tag sewn into the bottom corner of the screen. It looks like a mattress tag.

If you stand behind the screen, facing the audience, it will be on the bottom, left corner.

[Gordon McLeod]

Seen more than a few screens hung backwards The back side of the MDI Northcoats are very shinny on the back side and the front coated side is dull Also usually they mark on the grommet band which is the back side of the screen

[Paul H. Rayton]

Another possibility to consider could be that it may have been a "silver" screen, for 3D. What you are seeing now may be the aged or degraded surface that remains, which you are now calling kind of "shiny". 3D screen surfaces are some variant of an aluminized treatment, with the metal content allowing the reflected image to retain the polarized light from the projector.

One trait of "silver" screens, even new ones, is that they tend to "hot spot", i.e. the apparent reflected light seen from the screen is hotter (brighter) in some areas than in others. The hot "spot" will move, according to your position in the theater, so if you're off toward the left of the seating area, the viewable hot spot is off to the left of center. If you're off to the right, the hot spot will appear toward the right side of the screen. Next time you're in there, try moving from one side to the other, and see if the image (and any apparent extra brightness) moves with your movement. Ideally, you would do it with a still frame projected on the screen (and no audience present), so that the subject of the image on the screen is consistent. If there's a hot spot, and its location moves as you move, you've got a silver screen which may be damaged.

I mention the possibility of it being an older 3D screen because the "silver" (which, of course, isn't silver) surface is rather delicate; if that surface has been brushed or washed by someone in the past, in a well-intentioned but inadvisable attempt to "clean" the screen, something such as you are observing could be the result.

[Mike Reed]

There are different types of coatings on screens, particularly gain screens. Depending on manufacture and storage, they can definitely decompose and get this sticky like sheen on them. I have also seen screens get installed with the wrong side out (more than once). I believe MDI puts, at the bottom-center an indication of which side should be the front side or the back side.

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.

[Mark Gulbrandsen]

Shine a flash light on the front and then the back. assuming matte white the coated site will reflect light much smoother than even a semi glossy back. Plus I have received screens in the oast with no tag!!