Browse:
You are here: Home > Projector Screen FAQ

Projector Screen FAQ:







1. What does "Gain" or "Screen Gain" Mean?
Screen Gain is a measure of reflectivity of light compared to a screen coated with magnesium carbonate or titanium dioxide, when the measurement is taken for light targeted and reflected perpendicular to the screen. Titanium dioxide is a bright white color, but greater gains can be accomplished with materials that reflect more of the light parallel to projection axis and less off-axis.

Frequently quoted gain levels of various materials range from 0.8 of light grey matte screens to 2.5 of the more highly reflective glass bead screens, some manufacturers claiming even higher numbers for their products. Very high gain levels could be attained simply by using a mirror surface, although the audience would then just see a reflection of the projector, defeating the purpose of using a screen. Screens with higher gain will exhibit more mirror-like properties, namely a bright "hot spot" in the screen, an enlarged (and greatly blurred) reflection of the projector's lens. Opinions differ as to when this "hot spotting" begins to be distracting, but most viewers do not notice differences as large as 30% in the image luminosity, unless presented with a test image and asked to look for variations in brightness. This is possible because humans have greater sensitivity to contrast in smaller details, but less so in luminosity variations as great as half of the screen.

In normal screens, the greatest intensity of light will be reflected at an angle equal and opposite to the angle of incidence, favouring ceiling-mounted projector setups, as this maximizes the apparent screen brightness. Glass-bead screens exhibit a phenomenon of retroreflection; the light is reflected more intensely back to its source than in any other direction. This is intended for setups where the image source is placed in the same direction from the screen as the audience. Users frequently report some hotspotting in such screens, although this type of screen is seen as desirable due to the high image intensity they can produce with a given luminous flux from a projector.

Back to Top ↑


2. What does 16:9 and 4:3 mean? I also heard about 1:1 projector screens, do I need one?

Notice all screens are measured diagonally! Please read the specifications of each item.

Diagonal
(viewable)
1:1 4:3 16:9 2.35:1
width height width height width height width height
70 49.5 49.5 56.0 42.0 61.0 34.3 64.4 27.4
75 53.0 53.0 60.0 45.0 65.4 36.8 69.0 29.4
80 56.6 56.6 64.0 48.0 69.7 39.2 73.6 31.3
85 60.1 60.1 68.0 51.0 74.1 41.7 78.2 33.3
90 63.6 63.6 72.0 54.0 78.4 44.1 82.8 35.2
95 67.2 67.2 76.0 57.0 82.8 46.6 87.4 37.2
100 70.7 70.7 80.0 60.0 87.2 49.0 92.0 39.2
105 74.2 74.2 84.0 63.0 91.5 51.5 96.6 41.1
110 77.8 77.8 88.0 66.0 95.9 53.9 101.2 43.1
115 81.3 81.3 92.0 69.0 100.2 56.4 105.8 45.0
120 84.9 84.9 96.0 72.0 104.6 58.8 110.4 47.0
125 88.4 88.4 100.0 75.0 108.9 61.3 115.0 48.9
130 91.9 91.9 104.0 78.0 113.3 63.7 119.6 50.9
135 95.5 95.5 108.0 81.0 117.7 66.2 124.2 52.9
140 99.0 99.0 112.0 84.0 122.0 68.6 128.8 54.8
145 102.5 102.5 116.0 87.0 126.4 71.1 133.4 56.8
150 106.1 106.1 120.0 90.0 130.7 73.5 138.0 58.7

Notice all screens are measured diagonally! Please read the specifications of each item.

The screen geometry, such as 16:9, 4:3 or 1:1, means the aspect ration of the screen. The aspect ratio is its width divided by its height.For instance, the aspect ratio of a traditional television screen is 4:3, or 1.33:1.High-definition television and European digital television use an aspect ratio of 16:9, or about 1.78:1.

1:1 projector screen is a square-shaped screen, which is used for overhead projectors in most cases. These screens have an aspect ratio of 1:1 by definition. (Remember the old days? We used transparent slides and overhead projectors for presentation.) Because of the rise of digital projectors,1:1 screen are getting outdated.

However, a 1:1 screen can be a great solution for saving space. For example, if your school has several different type of projectors, and you only have space for 1 screen in 1 classroom, then a 1:1 screen will come in handy. The solution will accommodate overhead projectors and digital projectors at same time, save valuable space, and also keep the audience focused to one location.

Back to Top ↑

3.How big a screen should I choose for my projector in my room? Is there a tool available?

Screen size choice largely depends on the projector model and the distance between the projector and the screen. So there is no universal rule for it. Projector manufactures usually detail their projection size - projection distance relationship in the projector user guide. You can also use our new projector calculator to calculate.

(*The projection calculator is a tool provided for your convenience. Manufacturers may change product specs at times, so HTDepot cannot guarantee the metrics accuracy of any particular projector. For most accurate screen size VS projection distance information, please refer to projector manufacturer's user guide)

Back to Top ↑

 


4. Should I choose a 16:9 projector screen or a 4:3 one?

Choosing aspect ratio is a choice based on your primary needs. we suggest the following criteria for your to consider.

a. What is the primary use of screen? 16:9 widescreen formats are often used as dedicated home cinema use, respectively. 4:3 formats are more common in dedicated data presentation use.

b. What type of program you will be watching most using the screen? If you are primarily watching traditional television programs,4:3 video format can be a better fit; If your primary program source are DVD or HDTV, 16:9 format may be a better choice.

c. What is your projector's native aspect ratio? You can find that information from the projector manufacture. Here are some useful keywords, which can help you to find the information:

4:3 ratio keywords: VGA, SVGA, XGA, SXGA;

16:9 ratio keywords: 480p, 720i/p, 1080i/p

Back to Top ↑


5. I keep hearing about 720i, 720p, 1080i, and 1080p. What do these mean?

The number refers to the number of rows of information on the screen, and the letter refers to whether it's (i)nterlaced or (p)rogressive scan. In an interlaced format, the screen shows every odd line at one scan of the screen, and then follows that up with the even lines in a second scan. Since there are 30 frames shown per second, the screen shows one half of the frame every sixtieth of a second. For smaller screens, this is less noticeable. As screens get larger, the problem with interlacing is flicker. Progressive scanning shows the whole picture, every line in one showing, every sixtieth of a second. This provides for a much smoother picture, but uses slightly more bandwidth.

High Def Comparison Chart

Video Format Supported Native Resolution (WxH) Pixels (Advertised Megapixels) Aspect Ratio (X:Y) Description
720p
1280x720
1024x768
XGA
786,432 (0.8) 16:9 Typically a PC resolution XGA; also exists as a standardized "HD-Ready" TV on the Plasma display with non-square pixels.
1280x720
921,600 (0.9) 16:9 Typically one of the PC resolutions on WXGA, also used for 750-line video, as defined in SMPTE 296M, ATSC A/53, ITU-R BT.1543, Digital television, DLP and LCOS projection HDTV displays.
1366x768
WXGA
1,049,088 (1.0) 683:384
(Approx 16:9)
Typically a TV resolution WXGA;also exists as a standardized HDTV displays as (HD Ready 720p,1080i), TV that used on LCD HDTV displays.
1080i
1920x1080
1280x1080 1,382,400 (1.4) 32:27
(Approx 16:9)
Non-standardized "HD Ready", TV. Used on HDTV Plasma display with non-square pixels.
1080p
1920x1080
1920x1080
2,073,600 (2.1) 16:9 A standardized HDTV displays as (HD Ready 1080p) TV, that used on LCD/HDTV displays. Used for 1125-line video, as defined in SMPTE 274M, ATSC A/53, ITU-R BT.709.
2160p
3840x2160
3840x2160 8,294,400 (8.3) 16:9 Quad HDTV for DCI Cinema 4k standard format, (Currently, there is no HD Ready 2160pQuad HDTV format until 2015).


Back to Top ↑

6.Should I choose a grey screen? What is the advantage of a grey screen?

A relatively recent attempt in improving the perceived image quality is the introduction of grey screens, which are more capable of darker tones than their white counterparts. Contemporary grey screens are rather designed to have a gain factor similar to those of matte white screens, but a darker appearance. A darker (grey) screen reflects less light, both light from the projector and ambient light. This decreases the luminance (brightness) of both the projected image and ambient light, so while the light areas of the projected image are dimmer, the dark areas are darker; white is less bright, but intended black is closer to actual black. Many screen manufacturers thus appropriately call their grey screens "high-contrast" models.

In an optimal viewing room, the projection screen is reflective, whereas the surroundings are not. The ambient light level is related to the overall reflectivity of the screen, as well as that of the surroundings. In cases where the area of the screen is large compared to that of the surroundings, the screen's contribution to the ambient light may dominate and the effect of the non-screen surfaces of the room may even be negligible. Some examples of this are planetariums and virtual-reality cubes featuring front-projection technology. Some planetariums with dome-shaped projection screens have thus opted to paint the dome interior in gray, in order to reduce the degrading effect of inter-reflections when images of the sun are displayed simultaneously with images of dimmer objects.

Grey screens are designed to rely on powerful image sources that are able to produce adequate levels of luminosity so that the white areas of the image still appear as white, taking advantage of the non-linear perception of brightness in the human eye. People may perceive many different luminosities as "white", as long as the visual clues present in the environment suggest such an interpretation. A grey screen may thus succeed almost as well in delivering a bright-looking image, or fail to do so in other circumstances.

Compared to a white screen, a grey screen reflects less light to the room and less light from the room, making it increasingly effective in dealing with the ambient light originating from the projector. Ambient light originating from other sources may reach the eye immediately after having reflected from the screen surface, giving no advantage over a white high-gain screen in terms of contrast ratio. The potential improvement from a grey screen may thus be best realized in a darkened room, where the only light is that of the projector.

Back to Top ↑

7. Can you explain what "Reconditioned: Grade A (or B) "means?

Reconditioned screens are results of customer returns, exchanges or canceled orders. They all individually inspected and/or repaired by a factory authorized screen specialist. Then only grade A and B products are offered to customer at a significantly discounted price. Reconditioned products came with up to 1 year warranty unless otherwise stated.

Grade A: May have minor dents-dings or scratches on screen case and/or remote, screen packaging may have been previously used, no mechanical malfunction, no damage to screen fabric, the viewing experience is not effected.

Grade B: May have dents-dings or scratches on screen case and/or remote, screen fabric may have minor blemishes or scratch, please refer to each product listing description for specific issue description. The issues are generally not noticeable when viewing projected images/movies. Packaging may have been previously used, no mechanical malfunction,

Reconditioned screens are of limited availability, first come, first serve.

Special return policy applies on refurbished ones: No return, no exchanges on reconditioned products. Carrier damages, if applicable, will be handled by shipping carrier insurance.

Back to Top ↑

8. Do you have instruction manuals available for your products?

We sure do! Click here to view our product manuals. As they are in PDF format, you must use Adobe Acrobat to view them.