New "laser" screen from Harkness (also: When should an undamaged screen be replaced?)

[Mike Blakesley]

Got an email from Harkness Screens today promoting their new-tech screen specially made for laser projectors. They are doing demos of it at CinemaCon.

While we're going to CinemaCon this year, I hesitate to book a demo seat since we are only one screen. Considering all of the demo times listed have fewer than ten seats left, I assume they would not think that was very cool. I'd hate to take a spot away from some guy looking to buy a dozen or a thousand screens.

But at the same time, it got me to wondering -- should I be looking at replacing our screen? It's nearly 15 years old at this point but is still spotless. My own opinion is our image looks pretty damn good, but (as usual) I'm always open to something that would give us a huge improvement.

[Marco Giustini]

if your light level is correct and you don't see anything on a white field, maybe there is no need - if the screen has yellowed, that is compensated for by the projector MCDG.

However, chances are that a new screen would massively increase your brightness level - requiring a smaller lamp or less current.

And with that I do not mean a high gain screen and a "brighter hotspot" of course, I am talking about average brightness across the screen.

What type of screen do you have now? White, silver, what gain?

[Mike Blakesley]

It's a white Harkness screen, I'm not sure what the gain is, though -- maybe Mark G. could chime in on that since he installed it back in the day!

[Marcel Birgelen]

All screens with a gain above 1 will lead to hot-spotting. If your light levels are fine right now and you're not suffering from speckle or other annoying artifacts, then I'd say: Leave the screen alone.

I'm not sure what this "Laser screen" actually brings to the table. Randomized perforations to reduce speckle? Higher gain without causing speckle?

[Mike Blakesley]

I haven't seen any speckle or hot-spotting. Here's the blurb from their website:

More than five years in the making and developed alongside educational institutes, projector manufacturers, exhibitors and the Hollywood community, this exciting new technology will help exhibitors leverage the benefits of laser projection such as high dynamic range and wider colour gamut whilst reducing laser speckle by up to 30%.

We don't allow smoking in the theater but of course we DO allow popcorn-making, so if there's anything on the screen it's that (and dust).

[Steve Guttag]

Barco has their new screen too. Mike, seriously, I'd book the seat. You are an exhibitor going to a trade show. That is the EXACT reason for them doing demos. Go see for yourself what it is all about and don't feel "guilty" for not being a chain.

Now, as to screens...the lower the gain, with 1.0 being ideal, the better and if you are hitting the light specs (14fL +/-3) without driving your projector hard...there is no need to change the screen.

From what I've read, Harkness is promoting the screen as a reduced speckle screen. Speckle is normally a problem, increasingly with higher-gain screens, with silver being the worst. Speckle is but one factor in laser projecting. Hot spots/uneven light are the issue with gain screens. No matter what some manufacturer touts as their screen, somehow defying physics, as the gain goes up, so does the unevenness of the light. Ask them to show their PSA chart on the screen with a 2.39:1 ratio (a PSA...is a USL light meter that, displayed 45 light readings, at once in a 9x5 grid). It, pretty quickly, gives one a good idea of how even the screen is and when setting up 2-projector film theatres, a very handy tool for getting balanced light. For lasers, it is key on adjusting cold mirrors to evenly illuminate the integrating rod. The industry really needs that meter though it is no longer made.

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[Leo Enticknap]

I guess that a direct answer to Mike's question could be when you can no longer light the screen to a reasonably even 14ft-l with enough headroom to allow for the decline in the bulb's output over its lifetime (or avoiding having to run lasers maxed out), you once could, and you have ruled out anything in the projector as being the cause; or if you install a new projector, the math suggests that it should be able to light the screen comfortably, but in reality it can't. This was the case with an arthouse I installed an SP2K-9 in a couple of years ago. The online Barco number cruncher thought that it should give 14ft-l in 'scope with the lasers on 72%. Once installed, it only gave me 12.something maxed out. It turned out that the old and yellow screen was the culprit: once replaced, the projector's performance was as predicted.

This inevitably reminds me of the time I was cold called by someone whose decades-old screen had tears and stains on it, and he thought that the time had come to replace it. He asked me for a ballpark cost. I told him that Sales would need to come up with a proper quote, but gave him a rough figure based on his guesstimate of the size. His response: "That much ... just for a big 'ol white sheet???!!! Man, that's a shovin' it right up my poo hole!"

I resisted the temptation to reply that a movie theater screen would need to be rolled up very tightly to enable that.

[Mark Gulbrandsen]

Normally Screen Manufactures will send a sample out to interested theaters. So I suggest that you start by doing that. I'd ask for a 24" square piece. Have someone hold it in front of your present screen so you can make a comparison. Do it with just the room lights on and compare how white they look. Then run some content on it and decide what to do from there. I did this with quite a few customers over the years, and they always ended up buying a new screen.

[Harold Hallikainen]

I was also thinking of a sample screen but put it in front of the existing screen and measure it with a spot meter and then the existing screen next to it. How do they compare?

[Jim Cassedy]

I'm somewhat disappointed that the TV show "How It's Made" never visited a theater
screen factory. I've heard it said that the major screen manufacturers are very secretive
about their processes, but but I've always been very curious about how it's done.
Do they start off with a bunch of holes and then build a screen around them, or is
it the other way around?

[Randy Stankey]

I imagine it would be like a scene shop, backstage of a theater, where they lay out stage goods to clean them and sew them up.

You know... Giant tables with racks to hold oversized bolts of material and all that. I couldn't hazard a guess as to whether they manufacture the screen fabric, itself, or whether they have it made by some other company to their specs but the process of physically building a movie screen can't be much different than making something like a 20' X 40' grand drape for a stage theater.

[Ryan Gallagher]

Sailmakers lofts might be a decent parallel to "imagine". I'm most curious about how they apply the various "enhancements" on the high gain screens.... be it silvering or what-have-you.

There are tons of continuous fabrics that big in theatre... scrims, cycloramas, RP panels, etc. But none quite as "delicate" as a film screen.

[Marcel Birgelen]

Do they start off with a bunch of holes and then build a screen around them, or is
it the other way around?

It depends on whether you order a screen with holes or holes with a screen.

[Sam Chavez]

Stewart is the only company I know of that actually sprays their own vinyl onto a metal form. Very secretive. The other companies I'm aware of buy vinyl rolls and seam it, perforate it, edge it and spray it with coatings to achieve the desired size and gain.

[Randy Stankey]

There are tons of continuous fabrics that big in theatre... scrims, cycloramas, RP panels, etc. But none quite as "delicate" as a film screen.

Absolutely! I was imagining an environment like a cross between a scene shop and a Class 1 clean room.