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-   -   ALR Screen Brightness... HELP!!!! (https://www.avsforum.com/forum/23-screens/3068334-alr-screen-brightness-help.html)

jbail804 05-19-2019 09:17 AM

ALR Screen Brightness... HELP!!!!
 
I just purchased a 1.4 gain ALR screen. Watching it for the first time last night I noticed something I did not expect. The screens brightness seemed less than what it was when using a 1.0 gain white screen. This occurred at night, with all the lights off. The only source of ambient light was what was being reflected off the walls and ceiling (white ceiling and beige walls). I had to bump my power mode up from the usual "ECO" to "NORMAL" to get the same perceived brightness out of the screen. To make sure I was not just imagining this, I went out and grabbed a piece of the old screen and draped it over the new screen. Sure enough, the white 1.0 gain screen looked brighter (both to me and my wife) than the ALR Screen on real content as well as test patterns I pulled off of you tube. I understand that the two screens operate under different principals, and that white screens can be perceived to be brighter. I could accept this perceived difference argument if I were to comparing say a 1.0 gain white screen to a 1.1 gain ALR screen. But a supposed 40% increase in brightness being perceived to be 10%-20% less bright does not seem plausible to me. I do not have any experience with either positive gain screens or ALR screens. I can't get my head wrapped around this. Any insights, thoughts or observations you can provide me would greatly be appreciated.

Don Stewart 05-19-2019 11:54 AM

1 Attachment(s)
Quote:

Originally Posted by jbail804 (Post 58068890)
I just purchased a 1.4 gain ALR screen. Watching it for the first time last night I noticed something I did not expect. The screens brightness seemed less than what it was when using a 1.0 gain white screen. This occurred at night, with all the lights off. The only source of ambient light was what was being reflected off the walls and ceiling (white ceiling and beige walls). I had to bump my power mode up from the usual "ECO" to "NORMAL" to get the same perceived brightness out of the screen. To make sure I was not just imagining this, I went out and grabbed a piece of the old screen and draped it over the new screen. Sure enough, the white 1.0 gain screen looked brighter (both to me and my wife) than the ALR Screen on real content as well as test patterns I pulled off of you tube. I understand that the two screens operate under different principals, and that white screens can be perceived to be brighter. I could accept this perceived difference argument if I were to comparing say a 1.0 gain white screen to a 1.1 gain ALR screen. But a supposed 40% increase in brightness being perceived to be 10%-20% less bright does not seem plausible to me. I do not have any experience with either positive gain screens or ALR screens. I can't get my head wrapped around this. Any insights, thoughts or observations you can provide me would greatly be appreciated.

If the screen is TRULY 1.4 gain, then it should be 40% brighter when viewing at zero degrees on screen axis.
The attached photo below is a split screen comparison with a true and accurate 1.0 gain matte white screen and a true and accurate 1.0 gain ALR screen.
Notice that the white lights on the bridge have the same brightness value.

jbail804 05-19-2019 01:00 PM

Quote:

Originally Posted by Don Stewart (Post 58069630)
If the screen is TRULY 1.4 gain, then it should be 40% brighter when viewing at zero degrees on screen axis.
Photo below is a split screen demonstration with 1.0 gain matte white and 1.0 gain ALR screen.
Notice that the white light on the bridge have the same value.

Don,
Thanks for the reply. I do see what you are referring to as far as the brightness of the white.

I just did a simple experiment that I think is relevant, I found a LUX meter app for my phone. I do not expect the meter to give me an accurate reading, but I would expect the relative readings to be different when the meter is placed in front of the white screen material vs the ALR screen material. I played a white screen video from youtube. The readings we constant with my observations. The LUX meter read higher when placed in front of the 1.0 gain white material and lower when placed in front of the 1.4 gain ALR material.

bud16415 05-19-2019 05:59 PM

It might help if you told us exactly what 1.4 ALR screen you bought. Many here have tested many screens and know what ones have true specs and what ones are exaggerated.

jbail804 05-19-2019 07:47 PM

bud16415
In fairness to the vendor, I don't wish to do so. The screen has gotten very good reviews inside and out of this forum. My suspicion is the wrong screen material was provided as the screen is available indifferent gains. I am working under the assumption it was an honest mistake and will be corrected. Like I said in my original post, I have zero experience with ALR screens as well as positive gain screens. I just wanted to seek out the expertise of this forum to either support my limited understanding on the subject or shed some light to facts and characteristics that I might not be aware of. My goal is to gain knowledge (no pun intended), not to out the vendor for what I am assuming is an honest mistake.

rekbones 05-19-2019 08:07 PM

What are you using for a projector? The placement of the projector relative to the screen also has an impact. If a UST projector is used then the ALR screen must be designed for UST only. For standard ALR the farther the distance from the screen the projector is the less likely you will get hot spotting.

bud16415 05-20-2019 05:49 AM

Quote:

Originally Posted by jbail804 (Post 58071602)
bud16415
In fairness to the vendor, I don't wish to do so. The screen has gotten very good reviews inside and out of this forum. My suspicion is the wrong screen material was provided as the screen is available indifferent gains. I am working under the assumption it was an honest mistake and will be corrected. Like I said in my original post, I have zero experience with ALR screens as well as positive gain screens. I just wanted to seek out the expertise of this forum to either support my limited understanding on the subject or shed some light to facts and characteristics that I might not be aware of. My goal is to gain knowledge (no pun intended), not to out the vendor for what I am assuming is an honest mistake.

I don’t think anyone is going to view a screen company poorly if they made an honest mistake and promptly corrected it.

@rekbones is totally correct also to really offer help the folks here should know the projector, the screen, the throw distance and if it is ceiling or floor mounted. It would even be helpful if we knew the screen height and eye height and if offset or keystone was used in the setup.

To his point ALR works by rejecting light that comes from a steeper angle to the screen. If your projector is a shorter throw or a UST it will reject some of that brightness as if it was ambient light.

The screen company should have asked all these questions before recommending a screen material to you. :)

Dave in Green 05-20-2019 06:27 AM

@jbail804 , many people post satisfaction with their screens without actually measuring them with a light meter as you did and knowing for sure if the screen actually lives up to its claimed specification in the real world. Obviously the only two possible outcomes here are that the screenmaker resolves the situation to your satisfaction or they don't. Either way it will be helpful to other forum members shopping for a screen to know the specific screen brand and type and how the situation was handled. Forum members helping other forum members is one of the best qualities of AVS Forum. :)

jbail804 05-20-2019 11:46 AM

The projector is an Epson 2150. It is ceiling mounted on a 9 foot ceiling. So the projector height is around 8 feet off the floor. The top of the 130" Cinema scope screen sits 90 inches off the floor so about 6 inches below the projector. The throw distance is 19 feet. My seated viewing height is around 36 inches to eye height. Although it doesn't matter as I do not see any brightness difference seated or standing in front of the screen.

I will gladly reveal the name of the manufacturer in time. First things first. I want to be sure that there truly is a problem and it's not a newby mistake on my part. Once I confirm my suspicions, I will give them a chance to correct it. I will report the manner in which it is handled when the time is appropriate.

Sent from my SM-G960U using Tapatalk

Don Stewart 05-20-2019 12:32 PM

Quote:

Originally Posted by jbail804 (Post 58074364)
The projector is an Epson 2150. It is ceiling mounted on a 9 foot ceiling. So the projector height is around 8 feet off the floor. The top of the 130" Cinema scope screen sits 90 inches off the floor so about 6 inches below the projector. The throw distance is 19 feet. My seated viewing height is around 36 inches to eye height. Although it doesn't matter as I do not see any brightness difference seated or standing in front of the screen.

I will gladly reveal the name of the manufacturer in time. First things first. I want to be sure that there truly is a problem and it's not a newby mistake on my part. Once I confirm my suspicions, I will give them a chance to correct it. I will report the manner in which it is handled when the time is appropriate.

Sent from my SM-G960U using Tapatalk

Actually, you have a perfect set up for an ALR screen. With a 130" diag scope screen, your throw distance is near 1.9 times screen width. ALR screens perform at their best when utilizing longer projector throws.

Dave in Green 05-20-2019 04:57 PM

As @Don Stewart confirmed you have an optimum throw for an ALR screen. Nothing about your setup should cause an ALR screen rated at 1.4 gain to appear dimmer than a 1.0 gain matte white screen when viewed from the center of the viewing cone. From all the data presented it seems the two most likely scenarios are that you either received a lower gain screen material by mistake or you received screen material advertised at 1.4 gain that doesn't live up to the screenmaker's claims.

jbail804 05-20-2019 05:03 PM

Thanks every one for your input. I really appreciate you taking your time to help out a stranger. I'm out of town on a business trip this week, but will work with the supplier to exchange the screen when I return. I'll post the results as it gets resolved.

Sent from my SM-G960U using Tapatalk

Bruce Lowekamp 05-20-2019 07:28 PM

When I was looking for a new screen I got a lot of samples and measured them as well as I could, using an SLR and looking at the raw image file. You can find it in the forums maybe a year back.

The bottom line is that you can't believe your 1.4 screen is 1.4 and you can't believe your 1.0 is 1.0. I found a "1.0" non-ALR I measured at 1.4 and a "1.5" I measured at 0.9.

I would suggest focusing on whether the ALR looks good in your scenario rather than on the actual gain. If it rejects your problem light and has acceptable uniformity and you have enough lumens to light it, then it's doing its job. In my case my throw is shorter than ideal so the ALRs weren't uniform enough. I went with a grey screen instead.

Bruce

jbail804 05-21-2019 01:23 PM

Quote:

Originally Posted by Bruce Lowekamp (Post 58076574)
When I was looking for a new screen I got a lot of samples and measured them as well as I could, using an SLR and looking at the raw image file. You can find it in the forums maybe a year back.

The bottom line is that you can't believe your 1.4 screen is 1.4 and you can't believe your 1.0 is 1.0. I found a "1.0" non-ALR I measured at 1.4 and a "1.5" I measured at 0.9.

I would suggest focusing on whether the ALR looks good in your scenario rather than on the actual gain. If it rejects your problem light and has acceptable uniformity and you have enough lumens to light it, then it's doing its job. In my case my throw is shorter than ideal so the ALRs weren't uniform enough. I went with a grey screen instead.

Bruce

Bruce,
Good point and that is why I brought this subject to the forum. I assumed my "control" screen is a 1.0 gain screen. It might not be. I didn't think about that possibility.

To your point, I if the screen's performance was meeting my expectations then I would be satisfied....but it's not. Perhaps it would if I had more lumens to through at it. The 2150 is rated at 2500. I expected to have to run the bulb brighter when dealing with ambient light, but I didn't expect to in the dark. Before (at night) I got a good picture with the lamp in ECO mode. Now I have to run it in NORMAL mode where the noise of the fan is distracting. My fear going into this, was my screen was going to be too bright in the dark, but the reality is it's too dim.

bud16415 05-21-2019 03:59 PM

I don’t think too many advertised 1.0 gain white screen would ever be doing 1.6-1.8 or something like that to make up the difference you describe. The easy test is go get a sheet of copy paper and stick it up there. That will be close to 1.0 to tell you something.

The company has sent you the wrong material, but without knowing who it is we couldn’t say what product of theirs you might have received.

Dave in Green 05-22-2019 06:49 PM

@jbail804 , I was checking over some of your previous posts to see if there were any clues to your screen issues. With all due respect for your desire to keep the identity of the screen company confidential, you posted the following on this forum just two weeks ago so it's really already public knowledge and may be useful information to those trying to help you:

Quote:

Originally Posted by jbail804 (Post 58008882)
... I have purchased a 130" Dark Energy Pulsar 1.4 ALR scope screen to improve the daytime performance. ...

Since that company also markets <1.0 gain screen materials it's possible that you may have been shipped one of those by mistake.


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