Screen gain

[FNG212]

Is gain the primary spec to compare screens? This describes its reflective property correct?

What does 1.0 gain represent?

 

[jostenmeat]

1.0 should mean that whatever amount of lumens you throw at it is the amount that will be reflected. While I suppose it's considered a primary spec, there are other things that are just as important, and aren't really "specified". Things like uniformity, lack of hotspotting, ability to "disappear", stuff like that.

As with many specs, lumens is not always accurately specified. Many mftr's overrate this spec, as do many receiver companies do with their power ratings. While I can calculate FL by doing simple math such as Projector Lumens divided by Square Footage, multiplied by gain . . . that's just a paper spec. A sort of reference point, but not really accurate if you get my drift.

I use a retro-reflective screen, very high gain, and it reflects towards where the light comes from. By far most screens are angular reflective, and will reflect angle like a pool shot off a bumper. Or like an audio wave off your sidewall.

Some high value screens such as Carada are known to have excellent uniformity, but the cost of this uniformity could be more scattered/reflected light, for instance. There are always trade offs it seems, no matter what you choose. There are those who believe the only way to fly is with acoustically transparent, but then others will tell you that nothing will look as good as having an optical coating (which negates AT) . . . for instance.

Good luck.

 

[BMXTRIX]

Let's go ahead and add to this that while you can compare some screen specs, there are other things to consider.

1. The angle of view. That is, if people are going to be sitting to the edges of the viewing area, you want everyone to have a nice bright image. (This is part of image uniformity).

2. Construction: A POS screen can lose tensioning on the material, it can stain easily or fade easily. It can be thin material, or weak support structure. A good frame is the single most expensive part of most fixed frame screens.

3. Material color: While there is continuous discussion about this, the bottom line is that grey screens can enhance contrast in less than favorable room conditions. Yet, typically they cost you some gain. So, you need a brighter projector, which often ALSO costs you some contrast. Kind of a double edged sword.

Frankly, it depends on your budget and requirements. We all want a nice positive gain, light ignoring, acoustically transparent, perfectly uniform screen with complete masking and optional motorized (tab-tensioned) functionality for a hundred bucks or less.

But, the reality is that from a couple hundred bucks to a few thousands of dollars there are some options which are priced accordingly.

 

[rmk]

I found the screen in my FP system to be the most surprising element. Prior to “upgrading” my projector I had been advised to get the best screen possible. I received samples from several manufacturers and was able to freeze frame several 1080P images with a lot of contrast variation and hold the samples up and slide them across the surface of my old screen (Elite CineTension II). I had several friends watch while I did this and then I watched from several seating positions. Really amazing what the various gain and color screen materials do to the picture.

I highly recommend this technique as you will learn a lot about screen color and gain in your specific room and light conditions. It caused me to spend more than I expected on the screen, but it really paid off in PQ.