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There are many types and sizes of video and data projectors available today. This guide is designed to give you a brief overview of the technologies, important factors, and differences between them all, to help you choose the best and right one for your requirements.

 

Alternatively, call us at the Hire Division, and we will help you decide.

LUMENS
The brightness of a projector is measured in Lumens. The more Lumens a projector can produce, the bigger the picture can be, and the brighter it will be. The ambient light in the room or place that you are going to project is the most important factor regarding the brightness of the projector.

Imagine you have a cheap torch bought from a garage. In a power cut at night, this will allow you to easily see your way around, but at midday on the beach, it will only illuminate things that are very close to you, if at all. So the ambient light in the area that you will project in, is the important factor regarding the brightness.

Typically, newer desktop projectors are between 1,000 and 4,000 Lumens. Professional projectors are usually more than 4000 Lumens up to the brightest available today, around 25,000 Lumens.

Hire Division desktop projectors for hire are all above 3000 Lumens.

XGA and VGA
Cheaper projectors are lower resolution than XGA, which means the image will be of poorer quality and more blocky. Older computers used to run in VGA (640×480) and web sites and desktops running at this resolution look very old fashioned and “large”. The middle of the road is SVGA, most projectors can handle this (800×600) and will usually accept higher, and scale it down (or make it fit). XGA is the acceptable standard (1024×768), and SXGA is one of the higher quality resolutions available. A “W” in front of a resolution type is for Widescreen, where the ratio will then be 16:9 or 16:10.
Screens
There are many types of screen. When projecting from in front (front projection) it is important to understand that the screen material is reflective, therefore it really does make an enormous difference to the brightness and quality of the picture, as the image is reflected back at the viewer. So a screen is VERY preferential versus a plain wall. In fact, it can easily double the brighness of a projected image, compared to a wall or other surface.

With rear projection, you will need enough room behind the screen to position the projector at the right distance to ensure the image fits correctly, and the material is a special type of slightly transparent material. Most desktop projectors have lenses with a zoom to help with this, and of course, you will have to reverse the image, in order for it to be projected correctly. This can usually be seen in a menu in the projector.

Contrast Ratio
This determines the difference between the brightness and darkenss of the image, and therefore greatly affects the clarity. The higher the better.

There are currently two main types of video projector LCD and DLP. There are a couple of others, but there are very few models available. (LED etc)

LCD
By shining a bright light through either a single full colour, or three transparent LCD panels (one red, one blue and one yellow), LCD projectors can project an image through a lens onto a surface. Smaller, lighter, lower in cost, this type of projector is the most widely used. Video quality is good, and computer imaging is very good. A zoom lens allows tremendous flexibility, and some projectors feature lens shift, allowing the image to be raised or lowered, and some sideways. A simple calculation can be used to find either the screen size, lens type or distance from the screen required from the other two measurements. See our HANDY LENS CALCULATOR for help with this.
DLP
In DLP projectors, the image is created by microscopically small mirrors laid out in a matrix on a semiconductor chip, known as a Digital Micromirror Device (DMD). Each mirror represents one or more pixels in the projected image. The number of mirrors corresponds to the resolution of the projected image. These mirrors can be repositioned rapidly to reflect light either through the lens or onto a heat sink. Either three modules are used, or a single module with a rotating colour wheel creates the colour effect.
Resolution
The resolution of a video projector refers to the number pixels that the panel, or panels consist of.

  • VGA (640×480)
  • SVGA (800×600)
  • XGA (1024×768)
  • SXGA (1280×1024)
  • HD READY (1280×720)
  • WXGA (1366×768)
  • WSXGA 1440×900)
  • SXGA+ (1400×1050)
  • UXGA (1600×1200)
  • WSXGA+ (1680×1050)
  • HD (1920×1080)
  • WUXGA (1920×1200)
  • WQXGA (2560×1600)

There are several others but they do not relate currently to smaller desktop projectors.
Generally, this tells you how detailed a picture will be. For powerpoint, XGA is usually preferable.

Lenses
There are two types of lens, fixed and zoom. A fixed lens will mean that the projector will have to be a specific distance from the screen for a specific image size. A zoom lens allows a certain amount of flexibility.

Some projectors have the ability to change lenses. A short throw lens allows the projector to be very close to the screen and still project a large image, and a long throw lens means that a projector can be very far away but still project an image that is not way to large. A formula can be used to calculate the distance from screen to projector, lens requirement and screen size. Our handy calculator is available for this.

Brightness
Brightness is measured in ‘ANSI Lumens’. In a darkened small room, 1000 to 3000 Lumens should be adequate, but where the projector may be positioned a long way from the screen, a very large screen, or if there is likely to be a lot of ambient light, then you should generally get the brightest you can.
Rear/Front Projection
A video projector can be positioned behind the screen, projecting onto a slightly transparent screen surface. This is discreet, and provides a slightly duller image. Front projection means that the projector is in front of the screen, possibly “flown” above the audience’s heads to avoid being seen, or at the very back of the room with a special lens, or in the audience, which then usually causes some seating issues. Menu settings will change the image so that it is displayed correctly, reversed for rear projection.
Hanging or Floor Mounted
Projectors can be hung from ceilings, trusses, etc using special brackets. In this case, the projector is usually hung upside down to allow for the upward image projection of most projectors. Menu selection will adjust the picture to be shown upside down, when hung.
Keystone Correction
When the projector is positioned above or below the specific ideal position for the design of the projector or lens, (ie in most cases) a certain amount of “keystoning” will occur. This is where the top or bottom of the image is wider or narrower than the other, giving a distorted look to the image. Keystone correction allows the user to correct for this by digitally adjusting the image to compensate.
Inputs
Most projectors feature many inputs including computers as a VGA connector, RGB, or DVI, plus videos in SVideo, Composite or component. HDMI is now also available on many models, as well as SDI and HDSI on professional series.
Signals
There are two main signal types, computer and video. They are very different, and can not be mixed together without specialist equipment. Most projectors have a computer and video input. The user must then select the input on the projector. This results in a “glitch”. Specialist equipment, such as the ISS 108 allows smooth transitions and mixing between the inputs.
Switching Inputs
Should a presentation require both sources, a projector will not usually be capable of smoothly transitioning between the inputs. In this case, a special unit is usually used to convert all the various signals to the same one, allowing the projector to be left on one input. It depends enormously on the event as to whether the video is changed to VGA/XGA, or vice versa. If you need advice on this subject, please call our support team on 0845 652 6677.
Distribution
On many occasions, a video or computer picture is required to be displayed in more than one place, perhaps multiple projectors or projectors and Plasma screens. If this is the case, then the signal is fed in to a distribution amplifier in whichever format is required, and the multiple outputs of this device are then fed via cables to the appropriate equipment.
 
Speak to a member of the team and get your quote today