Based on these plans, the projection image has a diagnal length equal to the length between the lens surface and the display surface (wall). Correct?
I am having difficulty in deciding where to setup my projector and thus how to design it. Many users, probably a large majority, do not hang the projectors from the ceiling. From what I can tell during my readings there are a few reasons why professional projector systems are using hung from the ceiling:
1. Probably the most eye appealing
2. Best viewing. The reason I touch on this is because many magazine (home theatre, home audio and video, etc) advise not to break a 2-1 ratio when comparing the distance of the seats ftom the screen and the width of the screen. In other words, if you want a screen that is 8' wide, you do not want to sit any closer than 16'. These numbers seem out of line to me. However, I do not have a setup to test these numbers.
The reason this can become a problem is because I would like to preferrably build a projector with the lens 4-5' off the ground with a level projection. Of course, with a structure 5' tall you do not want it in front of the couch. However, if I were to build the projector where the lens is 4' off the ground, and the lens is 10' from the projection screen, I would have a screen width of 8', height of 6', and the screen would go from 1' off the ground to 7' off the ground. Make sense? If not I have a spreadsheet you can use to do the calculations.
Now, the problem. As shown above, my screen width is 8' and if I had my projector directly behind the seats (as close as the projector can be with level projection or a big projector in the way), then my seats would be 10' from the screen. The ratio (discussed above) would only be 1.25.
According to the magazine sources listed above as well as simple searches on google, the image quality can be worsened for viewers by sitting to close. Can anyone verify their home theatre setup dimensions and maybe test out different setups so we can have an accurate ratio to base our home theatre designs. It would be nice to be able to classify quality deteriation. Such as less than 1.5 ration => extreme pixelization. 1.5 - 2.0 => some pixelization, etc. 2.0 - 4.0 => great image quality. 4.0+ => image quality reduced, corners become black.
Ok, I hope this did not confuse people too much. I apologize. I have attached the excel worksheet so maybe that can help. The unit scale is how many sub units per unit. So lets say we are using Feet. The scale would be 12, for 12 inches per foot. The lens height is how far off the ground the lens is. Very simple calculations, but interesting to see.
**** could not upload file ***
Please visit: http://www.ryanblair.com/xls/ratio.xls to download
****
If the guy who did the "hdtv" projector with samsung can reply that would be awesome. I believe he placed his projector on top of a stereo rack at about 4' or so.
Thanks guys.