Projector Information & Buying Guide
- What is a Projector?
- Projectors applications
- Key Display Technologies
- Projector Size Categories
- Projector Aspect Ratios
- Projector Resolutions
- Projector Brightness
- Throw Distance
- Stacking Projectors
- Interactive Projection
- 3D Projection
- Other Things to Consider
What is a Projector?
A Projector is an electronic optical device that uses a beam of light to project an image upon a surface. Slide projectors have been around for at least a couple hundred of years and film projectors have been around since the late 19th century.
Today, Projectors today are commonly called Data, Video or Multimedia Projectors. They hook up to your computer, Video Player (DVD, Blu-ray, etc) just like a computer monitor or Television. There are many types though which are generally categorized by Display Technology, Size & Weight or Use and have many features to choose from but they all have one purpose: To give you a unique and powerful communication tool that provides unparalleled opportunities to capture your audience's attention, educate and inform. Projectors can be found in and used in almost any type of public and private environments…. Back to Top.
- Conference Presentations & Video Conferencing
- Command & Control
- Education (Classroom, Conference Room, etc)
- Digital Media & Advertising (Digital Signage)
- Home Cinema
- Houses of Worship
- Lecture Halls & Auditoriums
- Medical & Scientific Visualization (2D & 3D)
- Military Simulation (2D & 3D)
- Post-Production & Film
- Theatrical Productions
Key Display Technologies:
DLP or Digital Light Processor chip is a semiconductor that uses millions of hinge mounted microscopic mirrors to reflect digital image onto a screen or other surface. The mirrors act like tiny little light switches by either tilting towards or away from the light creating either a “Light” or “Dark” pixel. Light reflected of a DLP chip is passed through a Color Filter (red, Green and Blue) which is either a ”Color wheel” in a single chip design or a “Color Filter Prism” in a 3 chip design.
LCD or Liquid Crystal Display is a chip made of liquid crystal filled grids that are controlled by electric fields, which enables the Liquid Crystals to act like a shutter that either blocks the backlight or lets the light pass through to light up a particular color filter. Since there are hundreds of thousands or pixels, the combination of open and closed pixels can produce a wide range of colors and shades.
LCOS or Liquid Crystal on Silicon is similar to DLP technology in that it is a reflective technology; however it uses liquid crystals instead of individual mirrors that are applied directly to the surface of LCD chip.
LED or Light Emitting Diode is light source technology that uses a semiconductor diode that emits a single color light. As the LED is only the light source, LED Projector Chips can be either DLP, LCD or LCOS. Back to Top.
Projector Size Categories:
Pico or Pocket Projectors are small typically handheld or small enough to fit in your pocket. Most of these have a LED light source and generally weigh less than a pound.
Ultra Portable or Micro Portable These projectors generally weigh between 1~3 Lbs
Portable or Mobile These projectors generally weigh between 4-6Lbs
Conference Room These projectors are the most popular size and generally weigh between 7~25Lbs.
Installation (fixed) or Auditorium these are very large projectors generally weighing between 25~100Lbs
Projector Aspect Ratios:
The two most popular/standard aspect ratios are 4:3(1.33) Standard and 16:9 (1.78) Widescreen. But let’s back up and discuss what An Aspect Ratio is. An aspect ratio describes the shape of an image mathematically (square or rectangle) represented by the equation 4:3 for example (using equal unit measurements of the width divided in to the height or just width-to-height) or just by the answer of the equation 1:33 if we are using the same example. Now a 4:3 Projector can display 16:9 images but there are some tradeoffs depending on which ratio you go with.
4:3 (1.33) Aspect Ratio sometimes referred to as Standard aspect ratio which corresponds with the fact that for years TV broadcasts were filmed and broadcasted in 4:3 aspect ration as well as photography and most computer output. 4:3 is probably still the most common projector aspect ratio out there. You can display a 16:9 image on a 4:3 projector just fine, but you will have black bars above & below your image and the image will appear smaller than it would on 16:9 projector. Back to Top.
16:9 (1:78) Aspect Ratio usually referred to as Widescreen* ratio which corresponds with the fact that…Well it’s wider. Most Movies since the 50’s and now all HDTV programming are broadcasted in 16:9. So if HDTV & Movie Viewing or computer output using one of the latest computer OS’s like Windows 7 or OS X will be your primary use of a projector, you should probably look at a widescreen projector. And you can still view 4:3 images with a 16:9 projector it will just be smaller than it would on a 4:3 projector and you will have black columns on each side of your image which will typically be centered on your screen.
*Now there are additional less main stream variations of the widescreen aspect ratio like 1:6, 1:85, 2.00, 2:35:1, 2:40:1 and 2:50:1 but there are few if any projectors that are made in those native format. You can get to those ratios by using a 16:9 projector and an auxiliary lens; it’s an expensive option that is only needed rarely.
So which is better? The one you need is better because it all depends on what your usage will be and what your viewing preference is …. It’s just that simple.
Projectors have two types of resolution: Native and Maximum.
Native Resolution A Projector’s native resolution is just the number of pixels it can use to display the image. The higher the native resolution the better the image, for example an SVGA projector has a native resolution of 800x600 so it uses 480,000 pixels to display an image. Now a projector with a 1920x1080 native resolution uses 2,073,600 pixels to display an image.
Maximum Resolution A Projector’s maximum resolution is the highest resolution it can process and display, which maybe higher than it’s native resolution. To do this the projector compresses the image (removes information) to make it fit the native resolution of the projector. This ability give you flexibility by letting less expensive projectors display higher resolutions, the trade off is you’ll have a lower quality image than if you had the projector with the higher native resolution.
So which should you get? Get the projector that has all the features you need and the highest Native Resolution that fits within your Budget. Back to Top.
Brightness is the light output of projectors is measured usually in ANSI (American National Standards Institute) Lumens. This is the standardized unit of measure for Luminous flux…which is a measure of the power of light perceived by the human eye. How bright your projector needs to be will be dictated by:
Where you are going to be installing or using it?
- A room with the lights off will require less brightness than a room with abundant ambient light windows or lighting.
- How large is the room? Is it a theater room or conference/classroom or a lecture hall, gymnasium or Auditorium?
- What is the throw distance and how big of an image do you want to project? As these two specifications increase so will the brightness needed to support them.
Throw distance is measured from the lens to the screen. Depending on the lens used on your projector, the “Throw ratio” (an equation of Throw distance/width of image which results in throw ratio value) of your projector or the distance it is mounted from the wall determines how big of a screen you need. Inversely, if you need a specific size screen/image then using the throw ratio of your projector you can determine how far from the wall the Projector needs to be mounted. If your projector has a throw ration of 1.5-1.8 then to get a 10’ wide image you would need to mount the projector 15’ to 18’ from the wall.
Keystoning (Keystone Correction) & Lens shift
Keystoning happens when a projector is setup so that it is not perfectly perpendicular to its screen. The effect of Keystoning is that your image will be distorted and trapezoidal instead of rectangular. This can happen both horizontally and vertically but most projectors have Digital Keystone Correction (Vertically) but currently only a few have a Horizontal Digital Keystone Correction. Now, Keystone correction will generally fix the shape of your image using a compression algorithm but this may also cause some distortion (because lens focusing capabilities work on equal distances, when your image is projected at angle it will be virtually impossible to keep the whole image in focus) and image quality will degrade which is due to the loss of pixels during the compression. For this reason placement of your projector is always key whether you are going to permanently mounted or be using it portably.
Lens Shift This feature refers to the ability for a projector to move the image on the wall without changing the location or orientation of the projector. Projectors can have Vertical, Horizontal or Diagonal (variable) movement capability, obviously variable is the most useful as it gives you the most flexibility. Lens shift is also preferred over Digital Keystone correction as it does not compress the image which should give you a better image. Back to Top.
Simply put it is just as its name infers, you lineup multiple projectors either Horizontally or Vertically to project a single, Brighter image. It can be challenging task as the images need to perfectly aligned but the advantages may out way the extra work during installation. These advantages include: Cost savings, generally (2) 3000 lumen projectors will cost much less than (1) 5000 Lumen projector and although you probably won’t get exactly double the lumens, it will be really close, within 10% +/- of 2X the lumens. Less down time, multiple projectors means one can go down and you’ll still be able to project even if it is not at optimum performance. Another advantage is lessened or possibly no shadows, since there are multiple projectors the presenter will be less apt to through a shadow on the presentation as they will not be able to be directly in front of each projector at the same time. Disadvantages to stacking projectors include more challenging Installation, increased Black levels so depending on the model you will have degradation in contrast ratios but these tradeoffs are not perceived b very many as reason not stack projectors.
Now here are some things to consider to try and make this option a less challenging endeavor. First, you should use all of the same model projectors. Also these projectors should include Keystone Correction, lens shift (preferably variable) and there are a few other advantages to this besides cost savings. Mounting, there are some specially designed “Stacking” Projector mounts. Additionally, there are even some projectors that are specifically designed for stacking and have available “Stacking Tools” that help with setup. The NEC NP1250/2250/3250/3250W projectors have a free calibration tool to match up 2 - 4 projectors using your computer and a web cam! Back to Top.
There are some projectors with built-in Interactive WhiteBoard (IWB) technology which allows the presenter to use the projector screen surface or whatever they are projecting on, even just a painted wall, like an interactive. Both Epson and InFocus were the first to bring this technology to market (InFocus was this 1st to bring it to market in late 2009 but Epson was not far behind with their solution in spring 2010) but now there are units from Optoma, ViewSonic, Hitachi and BenQ as well. Some of the solutions like Epson’s are pen based which means you need to be at the board or screen and others are wand based which means you can interact from almost anywhere in the room within 30 to 40’. Like interactive white boards these solutions work similarly to Graphics tablets or optical mice in that they work of a digital grid. Once the projector and pen or wand are calibrated together the user can interact with or annotate, create and more with whatever they are presenting. Back to Top.
3D ready or 3D Capable This feature is the ability to display 3D content that has already been created (it will not take your Rambo: first blood VHS and make it 3D). All of the readily available 3D capable projectors also require the use of 3D Glasses either (Active or Passive depends on the model of projector) for you to see the image in 3D. Although entertainment is thought of 1st for the use of this feature, it is also used in education, Medical & Scientific Visualization as well as Military Simulation.
How does it work? Most 3D imagery is pretty simple and can be traced back to stereoscopic photography. Basically a 3D image is created by taking two pictures at similar angles then overlaying the two images so they are just offset a little, then when you view this image or video through 3D glasses, the glasses blend or combine the two images into one image which creates the illusion of depth. Now you can also do this with different colored layers of the image but they are all similar principles that your 3D glasses combine to create an amazing 3D effect. There are many different types of glasses but they break down into passive or active. Passive glasses generally use polarized lenses that have different viewing angles. Active glasses work via an electronic shutter system that opens and closes essentially shutting of the input to one eye or the other in an alternating pattern to create the 3D effect. Back to Top.
Other Things to Consider
Something to consider when choosing a 3D solution, Some people can get headaches, nausea or even experience a seizure from the active glasses, for this reason and the cost difference (active glasses require batteries and can cost as much as $150-$200) most people prefer the passive systems.