Considerations for buying a projector

When selecting projectors the following four items are important considerations depending upon the application.  Keep in mind that increasing any of these typically introduces more cost.
• Resolution
• Brightness
• Weight and Portability
• Features

Resolution
The amount of data that can be displayed on the screen is a function of a projector's resolution. Resolution is the number of pixels the projector uses to create the image. The more pixels it uses, the higher the resolution. Resolution is generally shown in a form indicating the number of pixels horizontally the second number vertically, such as "1024x768". Refer to the table below for common names for different resolutions:

SVGA	800x600
XGA	1024x768
SXGA	1280x1024
SXGA+	1400x1050
UXGA	1600x1200

The best way to determine what resolution is necessary depends on the application.  If the primary use is PowerPoint presentations, displaying Excel spreadsheets or other typical business applications XGA is sufficient and are generally the best solution for the money.  If finer levels of detail are necessary consider a higher resolution.  Don't forget that the computer attached has to be capable of displaying this resolution as well.  You would be hard pressed to find a computer these days that can not display at least 1024x768.

Brightness
You can find projectors in a wide range of brightness options.  These are typically expressed in a measurement called lumens.  The brighter the projector the higher the number of lumens.  Be cautious brighter is not always better.  There are four primary considerations when choosing your projector's brightness.

1. How many people will typically be in the room? This determines the size of the image, you need to make sure that everyone can see it.  As the number of people in the room increases, the image has to get bigger. This will reduce the perceived brightness of the projector as the light is spread over a larger area.
2. How much light is in the room? A dark room will provide the best image regardless of projector brightness. However, most of the time some light will be necessary for taking notes and to allow the participants to interact. If you cannot dim the lights consider a brighter projector, just remember that increasing the brightness too much will make it too bright if the room is dark.
3. What surface is the image being projected on? This is probably the biggest factor, if there is a good screen with enough reflection of the image light even a low brightness projector will look fine.  If you have to project on a painted wall consider a projector with a higher brightness to compensate for the lack of reflection.
4. What is your application? Training or group discussions will require more brightness as the room will be brighter.  Photo shows can afford a darker room, and therefore less brightness.
   

Lumen Output Groupings

• Less than 1000 lumens - These are the lowest light output projectors and are the lest expensive.  The low light requires a darker room.
• 1000 to 2000 lumens - The next step up seems to be the most common for slightly darkened rooms.
• 2000 to 3000 lumens - These are high-performance projectors typically used in large conference rooms and classrooms.
• 3000 lumens and up - These are ultra-bright projectors they are used in a variety of large venue applications, including board rooms, conference rooms, training rooms, auditoriums, churches, concerts, nightclubs, and so forth.

Weight
Not much to say about this one, the smaller the projector the more portable it is.  Do you expect it to be moved a lot or stationary?  Consider going for a model with reduced weight if you intend to carry it around.

Features
As is the case with most items the features tend to add the wow factor but may have some use.  Consider this category the least important consideration.

• Zoom:   The advantage of zoom is that you can place the projector in different places and still adjust he image.  A unit with a zoom factor of 1.2:1 will only let you adjust picture size by 20%. You can often move the projector a foot or two either way and accomplish the same adjustment. If you have a fixed screen size you are trying to fill, even a small amount of zoom will make it easier to adjust the image to the screen.   Zoom settings typically range from 1.1:1 up to 2.0:1 or more. The higher the number, the greater the zoom range.
• Keystone Correction: If the projector will move a lot consider purchasing a machine with keystone settings.  The keystone effect happens when you project an image from any angle other than straight on, this results in an image that is not completely square. Many projectors now include a feature that corrects vertical keystone, which occurs when you are projecting downward or upward.
• Contrast: Contrast is the ratio between the brightest and darkest areas of the image. If there is lots of light in the room brightness will be a higher consideration than contrast.  With typical room lighting, a projector with 400:1 contrast and one with 1500:1 contrast will look almost identical.
• Video Signal Standards: Most projectors accept many types of video connections, the most important consideration here is to make sure the computer has an output that can attach to the projector.  It is hard to go wrong with the old standby VGA connector common to most computers.  However, if using modern laptops consider S-Video, DVI or HDMI.  Sometimes there are multiple inputs as well allowing one to connect multiple computers with different connection types.  USB connectors are becoming more common as well, USB typically makes connection very easy.

The risk of Single Sign-On

In any organization where single sign-on is being implemented it becomes extremely important to ensure accountability is retained.  Users need to be encouraged that they be the only one to log into a workstation.  If one person logs in, then all applications under the SSO umbrella will launch under the credentials of that user.  In an environment where one person logs onto a workstation then allows others to launch applications without first logging in as that other person, accountability is put at risk.

A core tenant of security is that every person (user) is uniquely identified to ensure that all actions of that user can be accounted for.  In many ways this is like an extension of the risk of sharing your password with others.