Choosing the Right Screen for Event Use
Written by Johnny Palmer - Head of Special Projects at SXS Events.
It is exciting times for those of you who are using video screens for events. The technology is moving ahead at the fastest pace I have ever seen. Most people now have High Definition Flat Screen TVs at home. These screens project a very good picture quality, and because people have this at home, they expect to see something as good or better when they attend an event.
This presents a lot of challenges for the event organiser including:
- Emulating the same quality at an event as people are viewing in their own living rooms
- Maintaining the brightness on the screen needed for good visibility. Typical event environments have high ambient light levels - meaning screens have to often be extremely bright to be visible.
- Ensuring that large enough screens are provided so that the audience are clearly able to see the screen. In the event environment the audience are usually standing some distance from the screen.
- Guiding the client towards a realistic expectation of what can be achieved within a budget. This particularly applies to the quality, size and flexibility of the screen used for the event.
So whether it is a presentation, promotional video, live feed or otherwise, giving our guests/audiences a great experience takes a lot of careful design and balance of technical compromises.
In this article I will cover the main types of video display units available with their respective benefits and limits. I will then discuss each of the main factors and compromises that need to be considered when designing a video system.
This article has been written for event managers and producers so the level of technical detail is appropriate for these professionals. I have avoided covering the full range of complex expectations, but do invite you to email with any specific questions. As always, read this article as an overview of the subject and not a definitive 'how-to' manual.
LED Screen Systems
LED screens have become a staple for large screens in high light levels over the last ten years. These systems work by using vast arrays of Light Emitting Dioides (LED) to produce red, green and blue light. The balance of these three "primary" colours allows for almost any colour to be produced, with an equal level of all three creating a "white" light.
It may seem strange that only three colours really exist, but this is similar to how most print media and TV screens work. LED screens are typically constructed from multiple panels bolted together. These panels are often approximately one square metre each and can be scaled from a small size right up to enormous structures for large festivals etc.
The main benefits of LED screens are:
- They are the brightest of all screen systems
- Many systems are suitable for outdoor (wet) use
- As they do not rely on any kind of projection the panels are quite thin (around 30cm) and do not require equipment such as projectors etc anywhere else in the audience or event space
- They are reasonably efficient on power
- They are flexible in terms of where and how they are set up. Options vary from integrating them into an outdoor structure, to ground-stacking, to having truck-mounted screens that can be set up in minutes
- Because they emit light directly (rather than rely on front-projection) performers and the public can walk in front of them without casting shadows
The main drawbacks are:
- The pixel pitch (more on this below) is much larger than other screen systems. At time of print a common pixel pitch is 15mm and the absolute best available is 6mm (at huge expense). This means that they are inappropriate for applications where the audience will be close to the screen
- They tend to be very heavy, which means large rigging systems need to be provided which can be costly in both time and money.
Generally speaking, where an event is taking place in an area of high brightness and a large screen is needed, LED is an obvious solution.
To the untrained eye LCD, OLED and Plasma look very similar and have similar properties and limitations. These screens are seen in most living-rooms and offices and vary from 17" up to 60" for LCDs and 110" for plasmas (as of December 2011, but they keep getting bigger)
Both of these screen options will typically work to High Definition resolution of 1080 lines. These screens are ideal for small applications where a light, high-quality and cost effective screen is needed. Also, the range of connectivity on these screens is often excellent, which make them versatile.
The key benefits of these screens are :
- Cost effective
- Lightweight, which means they can be rigged easily and quickly
- Attractive, which means they can be in plain sight without dressing or otherwise
- Good range of connectivity. A typical screen will have a VGA, HDMI, Composite, Component, DVI and S-video input, which means almost any video signal can be easily attached
- The level of brightness is generally fine for all indoor applications
The limiting factors include:
- The size of the screens is limited to 60" for LCDs and 110" for plasmas, although they are getting bigger all the time. Screens above 60" are not generally available in the mass market (as they are an excessive size for themass consumer market) and are therefore disproportionately expensive and best avoided for applications that do not need them
- Brightness is generally insufficient for daylight use. However, some of our 55" LCD screens have performed well when in the shade for outdoor events.
Projection has been strongly in evidence for large-scale screens since the first motion pictures, although the technology has moved forward significantly over the years. A projection system works with a projector shining a light image of the pictures, video or text onto a surface. There are many different types of projector which vary in resolution, brightness, size and cost.
The projection surface can be anything from a high-quality aluminium coated screen material (for high-end specialised 3D projection or cinema work), to a white wall (for simple and basic ambient projections), or even the outside of a building.
We have done some amazing events using these techniques. Typically, the projection screens used for events are a high-gainPVC-based material.
Projection systems can be an effective way of putting over a large image and are essential for presentations, conferences, awards shows and many live events that are held indoors.
The projector itself can be either in front or behind the projection surface; but in either configuration there cannot be any visual or physical obstructions between the projector and the surface. Also the material must allow the light image to transmit in such a way as to allow for clear and bright viewing, which is usually the case with back-projected screen surface, or water screens. One of the most critical factors to consider with projection is the projection distance. This is the relationship between how far the projector is from the screen, and how big the screen is. This has an impact on angle of light from the projector. This can be controlled by selecting the right lens and using zooms. Whilst a range of lenses are available for our projectors, this can be a delicate design consideration as one must consider angles, loss of gain through air particles, amorphic shifts and venue spacing. An experienced projectionist will understand all of these factors.
For the purpose of keeping things simple, measure the width of your screen and double it - that will give you an easy projection distance with which to work. Working to this rule of thumb will mean uou can use standard equipment.
We are able, however, to work with almost any projection configuration using specialised lenses, bounce mirrors, blending and other tools.
Screen Size and Field of view
A question for you: Is a 10' wide screen big?
If you are sitting 20' away from it yes - and it would be uncomfortably large for presentation purposes. If you are sitting 200' away from it? No - and it would be almost impossible to read even the largest text without a telescope!
The point here is that screen 'size' is subjective but instead based on the concept of 'field of view'. This is how much of your viewing space something uses up . Imagine holding a piece of paper 2'" from your face, it will use up most of your field of view. Pin the same piece of paper on the wall opposite you and it will use a small part of your field of view.
So when you are thinking about video screen think about how much of the audience's field of view it will use. When you work this out you need to consider both the closest and farthest seat from the screen, taking into consideration the visibility from both points. The size of a screen will also be determined by the content being screened. If the screen is to show a single sponsor logo then a large screen may not be needed. However, if the screen is to show highly technical and text-rich drawings for a conference a very large screen will be needed.
It is always important to put in place the correct resources which are determined by the application for which is it is intended.
This if one of the factors of video that people get wrong a lot. Whilst a video system might look perfect in an office, it may be nearly invisible in a bright event space. Most people don't realise it, but outdoor light is over 100 times brighter than a typical office. The human eye has an incredible ability to adjust to these ranges of brightness without a person even noticing. This is why we must use the right equipment or a presentation may fail.
Brightness is measured in Lux point-reading; screen brightness is typically measured in lumens which is the relationship between area and brightness. Careful measurement and calculation by an experienced production designer will factor in all of these issues to ensure the correct solution is delivered for your event.
Resolution refers to the number of pixels that make up an image. A pixel is the single point that emits light. When many of these are working together they will create the impression of an overall image. To see this yourself look very closely at your computer monitor.
There are two ways that resolution is defined:
Total number of pixels - this is the total number of pixels a video screen can show and has no relationship to the screensize. For example a device may be labelled as "1080p HD". This means that it has 1080 rows of pixels and 1920 columns. This could be a small computer monitor or a large-format projector.
Pixel density - how many pixels are in a given area OR the distance between the pixels. see below "Pixel Pitch".
Generally the higher the resolution of a video system the better. More pixels means a more realistic image and a better viewing experience.
However, we have a lot of clients who ask for 1080p HD, which we will provide, but often the client will find that the content is not of a high enough quality. Any video system is only as good as its weakest link. So if we are providing a 1080p HD video solution and someone provides a standard DVD, or powerpoint in standard WXGA (a common computer resolution), the images viewed will only be as good as the system used and a lot of money has been wasted on cutting-edge technology.
So if your client requests HD video, make sure that all people providing content are aware of the required quality to maintain this. We would be happy to draft an email for you to send to all those involved.
For more info on this subject please read my article on PowerPoint here
Pixel pitch describes how far apart pixels are from each other. The term "DPI" (dots per inch) is a similar measure of this. Pixel pitch is important because if people can distinguish pixels to a high level they lose the overall impression of the imagery being shown.
The best analogy for this is that of a graphical mosaic - if you stand right up to such a mosaic it will just look like colourful tiles. As you walk back, it will then start to look like a "blocky" image. Walk back further still and eventually it may look like a perfect image. Video is exactly the same as it is also made of lots of small coloured tiles(pixels).
With video screens such as plasma screens, pixel pitch is not a consideration as you can stand 3' away from such a screen and it will look fine. LED Screens and projection systems can be a different story.
In all cases we will consider pixel pitch when we design your video solution. An important factor of this is the closest viewing distance for the audience. I hope that this has given you a good overview of some of the challenges and limitations to consider with video systems. I welcome any questions on this subject, or suggestions for any other future articles.
Johnny Palmer is founder and Head of Special Projects at SXS Events. He has produced in excess of 1000 events ranging from festivals, to awards shows, to private events and providing every aspect of event production. He writes numerous articles on matters relating to event production. He also guest lectures at various universities and colleges throughout the UK.
Johnny project manages SXS' premium projects and also offers guidance to other staff members for their projects.