There are several different types of projectors. Mine is a Digital Light Processing (DLP) projector. DLP apostles (of whom I am one) like it because the DLP image is sharp and has a lot of “pop”. The picture really jumps out at you and the blacks are very good. Most of the theaters you go to that use a projection system use DLP projectors.

If you watch 3D movies at the theater, you have probably noticed that you will occasionally get a dual image or “ghosting” in the picture on the screen. This is because in order to get the image to look like it’s in 3D, two images are projected on the screen from slightly different angles. The light from one image is blocked in one eye and the light from the other image is blocked in the other eye. The result is a stereoscopic effect and your brain interprets this to be a 3 dimensional image. Ghosting happens when some of the light gets past the filter that’s supposed to stop it. Those glasses you get at the theater don’t block 100% of the image meant to be blocked and so you get ghosting. These types of glasses are referred to as “passive” 3D glasses because they have no electronic components and just block the light coming in at a particular angle. They are therefore very inexpensive.

In my home setup, I have “active” 3D glasses which use what is called “DLP Link”. The projector sends an embedded signal to the glasses on a frame by frame basis. Because the glass to each eye is blacked out electronically back and forth from eye to eye, no light gets through that isn’t supposed to and you get virtually no ghosting. You don’t see the flicker because it happens so fast that your brain can’t process the delay. Think of a deck of cards with a drawing on each of a person walking that moves little by little. When you look at each card, you can probably see each picture is a little bit different and each card appears to be a discrete picture. Now, if you take that deck, look at the first picture, bend the deck back from the top, and let each card flip quickly forward, your brain sees a picture of a person walking and not individual pictures. The motion is smooth. Same with active 3D glasses and, in fact, your projector itself. It’s throwing up a sequence of static images that we see as motion.

If projectors, and DLP projectors in particular, are so great, why doesn’t everyone have one? Why don’t people spend less to get a bigger picture? Well, there are some disadvantages to home projectors. The main disadvantage is that a bright room washes out the picture much more than it does a regular flat screen plasma, LED, or LCD screen. In order to overcome this, you need a brighter light source. That means you pay more money. There have been strides made in this area and people are experimenting with alternative light sources that use less energy and don’t burn as hot. I think we’ll continue to see progress in this area. Another problem is since a projector shoots light on to the front of a screen, the image will be blocked if someone or some thing gets inbetween the projector and the screen.

One disadvantage that DLP projectors have is what is called the “Rainbow Effect” (commonly referred to as “RBE”). DLP projectors use a color wheel. If the color wheel isn’t rotating fast enough, some people will see flashes of green, red, and blue when a light colored object is moving across a dark area on the screen. Not everyone is sensitive to it or can see it. I’ve never seen it (and don’t want to). The slower the color wheel spins, the more likely RBE will be seen.

Projectors are an ideal solution if you have a light controlled room and don’t have a lot of people coming into, leaving, and walking across the room. If not, a big screen TV is probably your best bet. They do have some projectors that put out a LOT of light these days and, for these, you don’t have to worry as much about blocking light.