Bright reflection on PJ screen - AVS Forum
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post #1 of 13 Old 07-26-2014, 09:44 PM - Thread Starter
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Bright reflection on PJ screen

Sorry if this is a noob question, I did search but found only results on so called bright spots, I'm not asking about that.

Roughly just about center of my screen, directly where the PJ is aiming, there is a brighter area. I assume this is simply due the fact the my PJ is square on to the screen and it's essentially a reflection off the main bulk of the light being emitted.

Do other other people have this? Is it common or normal? Is there any kind of filter or something to counter it?

Nobody else has ever mentioned it so I suppose it's not overly obvious, but I personally have noticed it.

Cheers.
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post #2 of 13 Old 07-27-2014, 06:05 AM
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Quote:
Originally Posted by CoxyUK View Post
Sorry if this is a noob question, I did search but found only results on so called bright spots, I'm not asking about that.

Roughly just about center of my screen, directly where the PJ is aiming, there is a brighter area. I assume this is simply due the fact the my PJ is square on to the screen and it's essentially a reflection off the main bulk of the light being emitted.

Do other other people have this? Is it common or normal? Is there any kind of filter or something to counter it?

Nobody else has ever mentioned it so I suppose it's not overly obvious, but I personally have noticed it.

Cheers.
What your describing is called a Hotspot. It occurs mostly with high gain screens.
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post #3 of 13 Old 07-27-2014, 06:56 AM
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There are a few options depending on your room, projector, and the screen.

If your room is long enough and your projector can be moved back(farther from the screen) and zoomed to still fit the screen..that can help spread and weaken that bright center to make it a lot less noticeable. I don't know how far back you'll be able to go and still fit the screen, but every little bit helps.

If the screen is in decent shape, it might be worth a decent chunk of change depending on the brand. You might consider selling it and picking up a screen with neutral or nearly neutral gain. These not only look great in dark rooms, but also tend to cost the least because they are more simple to make.

If the screen is bothering you enough and is either in poor shape, not worth much money or you simply feel like selling would be a hassle, you could always paint it a neutral flat white or very light grey. That'll fix the hotspot no problem, but is only a last resort.
It is surprisingly easy in most cases and can even be done with a simple paint-roller using interior flat wall paint.

Dimming the projector (possible to dim further with an NDfilter) can help somewhat, but usually will just make both the bright spot AND the dimmer surround darker..so it'll still have a spot in the middle.

Last edited by Ftoast; 07-27-2014 at 07:01 AM.
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post #4 of 13 Old 07-27-2014, 06:57 AM
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Quote:
Originally Posted by CoxyUK View Post
Sorry if this is a noob question, I did search but found only results on so called bright spots, I'm not asking about that.

Roughly just about center of my screen, directly where the PJ is aiming, there is a brighter area. I assume this is simply due the fact the my PJ is square on to the screen and it's essentially a reflection off the main bulk of the light being emitted.

Do other other people have this? Is it common or normal? Is there any kind of filter or something to counter it?

Nobody else has ever mentioned it so I suppose it's not overly obvious, but I personally have noticed it.

Cheers.
This is a hot spot as was said. What projector, how far is it from the screen, what screen do you have.
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post #5 of 13 Old 07-27-2014, 10:15 AM - Thread Starter
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Thanks all for your replies. I can't go any further back with the projector.

Projector is a BenQ W1070.

Screen is this one (though was £320 new when I bought it): http://www.ebay.co.uk/itm/110-Premiu...item2c64ea3c5d

The throw distance is about 340 cm, or a bit over 11 feet.
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post #6 of 13 Old 07-27-2014, 11:20 AM
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Is yours the grey one or the white one?

Simple <$250 dedicated black-fabric theater room, build in a day, takedown in an hour.
Easy $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.
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post #7 of 13 Old 07-27-2014, 12:43 PM
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Quote:
Originally Posted by CoxyUK View Post
Thanks all for your replies. I can't go any further back with the projector.

Projector is a BenQ W1070.

Screen is this one (though was £320 new when I bought it): http://www.ebay.co.uk/itm/110-Premiu...item2c64ea3c5d

The throw distance is about 340 cm, or a bit over 11 feet.
If it's the screen with glass beads and a 2.5 gain, that would explain the hotspot. At just an 11 foot throw, I don't see how you can fix this apart from getting a screen with less gain.
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post #8 of 13 Old 07-27-2014, 05:00 PM - Thread Starter
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Mine is the white screen, I don't believe it's glass beads though. I read that grey screens are for lighter rooms, I can luckily get my room totally dark so went with a white screen. I clearly didn't read enough as didn't even know about hot spots!

Shame nobody makes custom filters where the provide rough size of hot spot and throw distance and a filter is make for your lens that slightly reduces the light let through in that area. Don't know if that's possible or if the physics work... sounds good in my head though.

Changing screen is a right faff, was very hard getting it upstairs, but if that's the correct (and only) solution then I may consider it.

I can get my room very dark, and may add electric blackout blinds behind the curtains for pretty much 100% darkness, in which case I suppose I could try lowering the brightness. Though as mentioned earlier I suppose there will always be a brighter spot in relation to the rest of my screen.
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post #9 of 13 Old 07-27-2014, 06:59 PM - Thread Starter
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I just flicked through a few movies with the sole intention of purposely paying attention to my hot spot, and really for the most part it's hardly noticeable. Certainly not enough to justify changing screens.

I will keep things as they are for now, cheers for the replies though, at least I know what it is anyway.

The only other thing that bugs me is I have a large nice oak coffee table, unfortunately this proves a nice surface which reflects light from the screen. Aside from getting rid of it, which I don't want to do, I believe my only solution is some kind of cover. Perhaps something felt or velvet in dark brown to match the wood, however I would want something that fitted perfectly.
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post #10 of 13 Old 07-27-2014, 07:08 PM
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Quote:
Originally Posted by CoxyUK View Post
Mine is the white screen, I don't believe it's glass beads though. I read that grey screens are for lighter rooms, I can luckily get my room totally dark so went with a white screen. I clearly didn't read enough as didn't even know about hot spots!

Shame nobody makes custom filters where the provide rough size of hot spot and throw distance and a filter is make for your lens that slightly reduces the light let through in that area. Don't know if that's possible or if the physics work... sounds good in my head though.

Changing screen is a right faff, was very hard getting it upstairs, but if that's the correct (and only) solution then I may consider it.

I can get my room very dark, and may add electric blackout blinds behind the curtains for pretty much 100% darkness, in which case I suppose I could try lowering the brightness. Though as mentioned earlier I suppose there will always be a brighter spot in relation to the rest of my screen.
If it's a low gain white screen, I don't see why you would have that much of a hotspot unless it's a poorly performing screen. A 1.0 or 1.1 gain screen shouldn't be giving you this kind of problem. It might be the length of your throw causing the issue. Have you tried just leaving the screen up and projecting on the bare wall to see if you still have the hotspot?
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Last edited by ben38; 07-27-2014 at 07:41 PM.
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post #11 of 13 Old 07-27-2014, 09:11 PM
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I agree with ben38. The only thing I can think of is that it might be a slightly off-white instead of a very bright white and the 1.1gain isn't only boosted by 10% (1.0 to 1.1), but could easily be a 38% boost (0.8 to 1.1).
It's really easy for a white to be a few points below 1.0gain and even the brightest flat paints are only 0.8-0.9gain if they don't have any sheen or reflective(sparkly) particles.

The problem IS the screen surface and it's made worse that the w1070/room can't hide it with a super long throw-distance. It really sounds like it was a fantastic price for a tab-tension screen and I'd be very hesitant to replace it.
You might be particularly sensitive to seeing it for whatever reason..it's just something that bothers you more than others.

Simple <$250 dedicated black-fabric theater room, build in a day, takedown in an hour.
Easy $25-40 DIY black/dark-grey ambient-light rejecting screen, grab two things from a local store..mix..roll..done.

Last edited by Ftoast; 07-27-2014 at 09:22 PM.
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post #12 of 13 Old 07-28-2014, 06:23 AM - Thread Starter
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I cant try it on the wall really, well I could but the walls are a dark colour.

I think it is just me, nobody else has ever noticed it and when I purposely looked for it yesterday it was hardly noticeable. I suppose it depends on the video content.
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post #13 of 13 Old 07-28-2014, 07:03 AM
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Is the projector new? The bulb will dim a bit over time. Maybe enough that you won't notice the hotspotting before long.

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