...I was thinking whether I can setup this cheap projector at home which will reduce the eye strain on my kids to an extend (assuming the image produced from a reflected surface wont be as intense as an LED TV). Your thoughts?
I know this matter is already resolved here, but I wanted to share my views and experience on this in case someone comes here through a search looking for info on this subject.
I work for long hours on a computer and my eyes used to get tired by evening when I saw TV for over an hour. I also had a similar thought that maybe reflected light from a projector would be better for the eyes than directly looking at the source of light when watching movies on a TV.
Now, after some experimentation and trials with different projectors, I can be sure that projectors actually strained my eyes more.
Here are the reasons, in my opinion, why a TV would be better if you are concerned about eyes (even better would be not to watch if you get eye pains, but assuming that you or your kids want to watch for some time):
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1) Darkness: The way the pupils of the eyes work is that they expand/dilate when there is less light and they contract/shrink when there is more light. When watching a screen in darkness, the light will fluctuate from very intense light to very dark in the same scene of a movie. The pupils have to keep adjusting to the brightness. That will tire the eyes more compared to watching the same movie on TV.
This is because when you watch TV, you keep the light on and so the pupils will mostly stay at the same size as the eyes are adjusting to the overall brightness in the entire room and specially on the wall behind the TV. The TV is also a much smaller size than the wall and so major changes in the brightness of the scene does not affect the overall brightness of the entire room. To explain this better, go into a dark room, turn off the light, turn it on, turn it off, and see how uncomfortable it feels if the major source of light in the room is fluctuating.
For those who think that getting a high brightness projector will allow you to see the picture in light, it doesn't work that way. Any light in the room washes out the image, specially black as projectors cannot project black and you have to bring your own black by keeping the room dark. Most people will prefer to turn off the lights again as the image becomes more clear.
2) Indirect Light is Still Light: When it is said that reflected light is better, it means that the ambient light in the room should give light to the object being viewed. For example, if you read a book or newspaper under a light, that is better than reading the same content on a tablet or mobile. That is also why Kindle or ebook readers are better than tablets or iPad for reading. However, when it comes to projectors, you are looking directly at the light source. You are not using the strong reflected light of the projector to look at something like a newspaper in your hands which does not emit any light.
3) Clarity/Contrast: A budget projector's contrast (under $2,000 or Rs.1.25 lakh) cannot match that of a TV. If you are considering a cheaper projector (under $300 or Rs.20k), then you or your kids will strain their eyes more trying to see the picture compared to watching a TV where everything is crystal clear. Not only is the viewing experience not very good, but those with sensitive eyes will get affected faster.
The high contrast of a picture gives a 3D type image. That means, you can clearly tell the difference between a face and the background behind it. Both sharpness and contrast help achieve this. But in a low contrast image, everything will appear to be in a single plane which means your eyes will have to strain more to understand what's in the foreground and what's in the background. This happens automatically without you knowing about it, but your eyes will get tired due to the lack of clarity.
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If your eyes are sensitive and you are still going for a projector, I would recommend doing a proper setup such as using a grey screen to get better black levels and keep some type of light behind the screen and not watch it in complete darkness.
1-chip DLP projectors also cause eye strain to some people and for those, 1-chip or 3-chip LCD (maybe even 1-chip DLP with LED lighting) is the only alternative. For more details on that, I have shared my experience with entry-level projectors in a different thread (titled "First experience with projectors").
For normal TV viewing, a TV is best suited for the job. Most people use projectors only for movies. I would not look at projectors as a TV replacement even though some people who love projectors do so.
Hope this helps.