Projection Screens

The purpose of a projection screen is to reproduce visual information without losing image quality and to distribute the projected light towards the audience; it plays an integral part in the quality of the displayed image. Projecting without a screen will compromise the image in one or more ways.

• Resolution loss
• Brightness drop
• Spectrum shift
• Hot spotting

How do screens work?

Projection screens maximize the light coming from the projector by reflecting more light back to the audience. They are made using high-tech paint and fabrics, that either focus or diffuse the light shining on them and control how that light is reflected back to the viewer.

A projection screen has to reflect and distribute the projected image in such a way that everyone in the room can see and read the image clearly, so optimum image quality can only be achieved if the projector and projection screen are perfectly matched to the room.

Types of Reflection

Screens can alter light in 4 different ways:

Diffusive – reflects with almost complete diffusion. Reflecting light in all directions

Diffusive

Reflective – reflects in the opposite direction to the source. If ceiling mounted, light is reflected from the screen to the floor.

Reflective

Retro Reflective – reflects back to the source.

Retro Reflective

Rear Projection - Light is difused through the screen

Rear Projection

What Size Screen?

The bigger the screen, the more lumens you will need. If you double the screen size - say from 60 inch. diagonal, to 120 inch. diagonal, you will need a projector with 4 times the brightness. If you think of a torch shining on a wall the larger the beam the lower the brightness. So a good idea is to work out the size of the image you want. This is not just as big as the wall. Remember that you should be at a distance from your screen less than 1.5 times its diagonal for that real cinema feel.

 

Screen sizes compared

 

Which Aspect Ratio? More

An aspect ratio describes the shape of a film image or a display unit, such as a television or a cinema screen. The aspect ratio of an image is the ratio of its width to its height.

Original TV's had an aspect of 4:3, meaning a ratio of 4 wide for every 3 high. This equates to 1.33:1 if divided out (4 divided by 3).

Generally when choosing the aspect ratio of your screen its worth taking into account the aspect ratio of your projector. If your projector is natively 4:3 match this with a 4:3 screen. This will give you the best effect filling all available screen space and optimizing the projected image.

Screen Gain Explained

With lower lumen projectors (below 500 Lumens), screens were a necessity to maximize the light and were generally "High Gain". Now with the high lumen projectors (anything above 2000 Lumens) it isn't so important to have a high gain screen.

Rear Projection

The latest ultra-short throw projector allow rear projection in very small spaces. Normally using a mirror that enables large images while maintaining a relatively slim profile for the home or in the boardroom. A permanent rear-projection system can be installed into a wall for a neater and more impressive finish.

Rear projection also have the benefit that people are less likely to walk between the projector and the screen, casting shadows over the image. They tend to be considerably more expensive than front projection.

Note: Rear projection reduces the visible brightness of the image. Upon reaching the screen, the majority of the light travels forward to the audience, but some light is reflected back from it. This can be up to a 40% reduction. Consider this before choosing your projector.

Different Types Available

Projection screens have been offered in a variety of different materials from ALR, to grey and silver. All of these have been shown to have benifits in certain situations and limitations. The main benifits are a high gain, to boost brightness, higher contrast where ambient light is an issue.

ALR Screen

Using the latest design, ALR screens are bright high contrast. They are a rigid screen with minimal hot spotting and excellent ambient light rejection. Their smooth surface is perfect for high resolution, 4K and 8K projection. Available but expensive due to high manufacturing and transport costs.

Image courtesy of Grandview

Grey

A grey front projection screen can improve image contrast. When there is any ambient or reflected light in the room, a grey screen will partially absorb the reflected light. Unfortunately, this results in a colour shift to the blue spectrum. Not a problem with black and white images. This can create ghastly problems with colour, skin tones have a green, sickly tinge and your whites will also be slightly off-white.

Image courtesy of Elite Screens

Silver

Silver lenticular screens also provide a higher gain, up to 2.4. However these screens will cause a colour shift to blue, have a smaller viewing angle and can hot spot. These screens are great for old black and white, low brightness projectors but not necessary for contemporary projectors. However, this material is still the best medium for 3D projection

White

White screens are by far the most popular screen. The only reason people look to other screens are because of enviromet or under powered projectors. Normally with a gain of 1.1, white screens display the image faithfully. If you have a room that has controlled lighting, this is you best option.

Image courtesy of ScreenTechnics

Projection Screen Paint

A good option in certain instances if to paint a wall. A painted screen can be cost effective, long lasting and less intrusive. But the right paint has to be used.

Not all screen paints are equal!

Projecting on an ordinary painted wall can scatter the light in the same way as the beaded screens. Standard white paint is never white! the slight yellow colour will move the colour spectrum of the projected image and can suffer from hot spotting while the overall image brightness can drop (see below).

Specially formulated projection screen paint is designed to stop spectrum colour creep, reduce hot spotting and increase the contrast. After testing over 5 different paints, we choose the best performing screen paint on the market - Scream (Screen Cream) paint products.

Scream Paint

In testing, Scream screen paint was found to be as good as leading screens, great for inconspicuous screens inside and outside. Simply paint the Whole wall white. It also has the flexability to be painted onto curved surfaces and glass for rear projection. Call sales for pricing.

• Spectrum Plus - for exceptional colour fidelity.
• Excellent gain with minimal hot spotting.
• Smooth Screen Technology - improves image sharpness
• Easy single-step application.
• Can be applied to glass

Actual Projected Image courtesy of Scream Screen Paint