Glass bead or matt white for Acer H5360BD

shadieb

Member
Just purchased the above projector from Amazon.de, and now looking for a decent electric remote screen to go with it, would like 100 inch +. Which would be better suited to the projector, glass bead or matt white screen?

Anybody got any recommendations on a suitable brand or able to recommend they are using?

Thanks for your help.
 

marcosscriven

Active Member
This is a very bright projector, and even in 3d I find just projecting onto a matte white painted wall is good.

I'm no expert, but anything high gain sounds like it would be too bright
 
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dovercat

Guest
If you do not get a tab tensioned screen then you may end up having problems with visible waves on the screen.

For an idea of image brightness, screen gain.
A piece of white xerox photocopy paper is about 0.92 gain


Glass bead screen

Advantages

It is high gain usually around 2.5, for brighter and more vivid image.

It is retro-reflective, light bounces back the direction it came. Reducing the amount of light bouncing on to the side walls, ceiling, floor, and the amount of the light bouncing back onto the screen from the room that is being directed at the viewer. This can improve contrast.
Screen waves, in the image, if the screen is not flat, tab tensioned, are less noticeable than with a non-retro reflective screen.

Disadvantages

Limited viewing angle for best results.
Retro-reflective, reflects light back the direction it came. The more off this angle you are the less gain you get, picture brightness drops of rapidly.
Ideally you want the projector long throw, the longer the throw the less the angle projector light > screen, so the wider the viewing angles.
Ideally you want the projector lens at most 2-3 feet above eye level. Depending on the projector offset this may mean having the projector tilted resulting in the image being say slightly wider at the top than the bottom, slight geometric error is not noticeable and I would not recommend using keystoning to correct it due to the loss in image sharpness.
Ideally you want to be sitting in line with the projector-screen, so only a couple of good seats.

It maybe way too high gain, raising black level too much so image lacks depth and causing very bad DLP rainbow effect. You can increase the height of projector to decrease gain to viewers. But I think that might somewhat defeat the point of a glass bead screen, and maybe likely to cause problems with image uniformity, uneven brightness. To lower projector brightness a camera lens ND neutral gain filter could be used, then removed as the lamp dims with age, or to increase brightness for 3D.

Screen has sand paper like texture, which maybe visible in some scenes, depending on seating distance. I find it rarely noticeable and not bothersome, glass bead to me seem to have no visible screen surface when looking at images projected on to them. However somepeople cite screen texture as the reason they find them intolerable? Sparkles might also be visible in some scenes depending on angles and brightness.
May have very slight hot spotting, uneven image brightness, more so if people are sitting off angle. But no where near as bad as angular reflective screens. I do not find it noticeable.

Very easy to damage, can not be repaired, can not be cleaned
Fragile handle with care, if glass beads get rubbed off then you have darker patches in the image
I do not know how long it will last being repeatedly rolled up, I have mine as a fixed screen.



Matt White screen

Advantages

Wide viewing angle
Screen uniformity of brightness

Disadvantages

Lower gain typically 1 to 1.2

Lights up the side walls, ceiling and floor more, and the light bouncing back on to the screen from the room bounces in all directions, reduces image contrast.

Depending on make of screen the screen texture maybe visible depending on viewing distance. If screen much higher than 1 gain it may have a sheen to it. If screen not perfectly flat - tab tensioned, it is likely to end up having visible waves on the image with a roll up/down screen.
 
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shadieb

Member
Thank you Dovercat, thats very helpful and insightful. I have learned more from your post then I have scouring the net for information.

Cheers.
 
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dovercat

Guest
You may want to use a camera neutral density 2 filter for 2D viewing even with a matt white screen, ND2 filter will half projector Lumens. With a glass bead screen you might need to use a ND4 filter for normal 2D viewing and a ND2 for 3D viewing, quarters projector Lumens.
Hoya glass filters are genrally recommended for projectors. You can use the cheap plastic filters to try out the effect ND filters have on the image, but the plastic filters might get some image reflections-ghosting.

(Projector Lumens / Image surface area in square feet) x screen gain = image white level in foot Lambert
Note screen gain with high gain screens like glass bead screens is very dependent on projector-screen-viewer angle, the gain spec is a max figure.

For a 16x9 screen with 1.0 gain, the required lumens are as follows

Screen size
100" 87.18"x48.98" = 29.7sqft x 12fL = 356 Lumens, 14fL 416 Lumens, 16fL 475 Lumens, 23fL 683 Lumens
110" 95.91"x53.88" = 35.9sqft x 12fL = 431 Lumens, 14fL 503 Lumens, 16fL 574 Lumens, 23fL 826 Lumens
120" 104.63"x58.78" = 42.7sqft x 12fL = 512 Lumens, 14fL 598 Lumens, 16fL 683 Lumens, 23fL 982 Lumens
130" 113.33"x63.67" = 50.1sqft x 12fL = 601 Lumens, 14fL 701 Lumens, 16fL 802 Lumens, 23fL 1152 Lumens
140" 122.05"x68.57" = 58.1sqft x 12fL = 697 Lumens, 14fL 813 Lumens, 16fL 930 Lumens, 23fL 1336 Lumens
150" 130.78"x73.47" = 66.7sqft x 12fL = 800 Lumens, 14fL 934 Lumens, 16fL 1067 Lumens, 23fL 1534 Lumens

The projector claims 2000 lumens in low lamp mode.
But it does not appear to specify video lumens, so that could of been measured at 9300K not 6500K and be significantly lower when calibrated for video.
If it has brilliant color or white peaking using a white segment on the colour wheel or wheel spokes, turning off the feature will also lower the white level and contrast but improve colour saturation of bright colours so it comes down to personal preference.
Lamps vary by up to 20% and can dim by up to 20% over the first couple of hundred hours of use. Lamp life is for half of lamps still working with at least half of rated lumens.
So 2,000 Lumens can be 1200-1000 Lumens or less in reality.

Using active shutter glasses 3D will drop the projector Lumens to 40% or less of the 2D Lumens due to the sequential nature and glasses. So down to 480-400 Lumens or less

The target fL for a screen are:

For projection in a dark room.
The DCI digital cinema specs are 14fL reference
DCI theatrical presentations tolerance 11-17fL
The SMPTE film print specs are 16fL open gate (about 12fL for 1.85:1, 14fL for 2.35:1 due to film transparency and lenses used)
SMPTE film print theatrical presentations tolerance 12-22fL open gate (about 9-16fL for 1.85:1, 10-19fL for 2.35:1)

Some people go by the video monitor in a dimly lit room, especially if they have ambient lighting in the room. They generally opt for about 23fL.

Video monitor specs are
EBU white level 70 to at least 100cd/m2 (20-29+fL) white, older versions of the EBU spec used to use 80cd/m2 (23fL) as an example of reference white level.
SMPTE 35fL, but according to some people in practice 23fL is used.

For comparison (I would not have the projector this bright, dlp rainbows would probably make it unwatchable)
Emulating displays in living rooms with normal lighting 200cd/m2 (58fL) is used, and consumer flat panels under 50" are recommended to be capable of at least that by the EBU, for adverse conditions upto 400cd/m2 (116fL) is used.

There is no codified 3D white level.
Due to the sequential and polarized nature of cinema 3D the white levels used in cinemas are very low.
3D films are mastered for the cinema according to Pixar for 4.5 white level, with theatrical tolerance 4-5fL. While according to some projectionists 3D films are 5fL reference with 4.5-5.5fL theatrical tolerance.

I would guess that 3D films remastered for consumer video is expected to be shown on 3D TVs using active shutter glasses that is a more light efficient process than used at the cinema. Assuming about 40% of normal video 8-12fL in a dim room, 23fL in a living room as a guess.
 
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shadieb

Member
Thanks again Dovercat, yoiu certainly know your stuff. I have opted for the matt white Panoview 106" electric remote screen. I needed something where the override switches were located on the screens housing and not on wires that need routing down the wall.
I will certainly have a play with the 2D brightness side and see how it goes. to be honest though the projector is primarily for 3D blu-ray and it appears to score well on that behalf.

Cheers.
 

marcosscriven

Active Member
You may want to use a camera neutral density 2 filter for 2D viewing even with a matt white screen, ND2 filter will half projector Lumens.
I have the same projector, and this sounds like a great idea. 3D looks really good on this, but 2D looks washed out.

What would you recommend to hold such a filter it in place? And how would you move it out of the way for 3D, and back again for 2D?

Marcos
 

nipbiplip

Well-known Member
marcosscriven said:
I have the same projector, and this sounds like a great idea. 3D looks really good on this, but 2D looks washed out.

What would you recommend to hold such a filter it in place? And how would you move it out of the way for 3D, and back again for 2D?

Marcos
I too would be interested to know mire about the filter and if it makes an improvement on the 5360

Also, which size filter would you use, and does it need to be up right against the lens?
 

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