The subject of viewing distance emerged as a spin off from a thread in the single lens (LCD, DLP, DILA) projector forum. I began a new topic in the screen forum because I thought this kind of discussion might be more appropriate here than in the thread where the subject arose.
In the other thread, I happened to mention the dimensions of my screen (7' by 14') while discussing a related matter. This prompted Bob Wood to ask how far away from the screen I sit when viewing. As I started to reply, I realized that simply saying 12 to 14 feet without some explanation might seem pretty outrageous in view of SMPTE recommendations. So, Bob, let me try to explain my approach to viewing distance as it has evolved over the years.
First, 7' by 14' is the screen size when the masking curtains are fully open. However, I do not use all of that screen area with my current projector (6 year old Sharp XV80U LCD, w/ VGA res). It's dated technology cannot project a decent quality image THAT large. The screen width is 14' because the approximate distance between my right and left front speakers is 14', and the 7' screen height leaves a 1' space for my center channel speaker below the screen. Since, the room is fully dedicated to the theater, I figured the wall between the speakers wouldn't have any other function anyway, if it wasn't anchoring a screen. So, I ordered the Draper fixed frame with the M2500 material to cover the entire 7' X 14' area. I knew it was too big at the time (1995), but I hoped the future would bring more capable, higher res projectors along with HD video. At that time, I also installed a Makita curtain system so I could mask off whatever portions of the screen I did not want to utilize. This set-up permits any size image and aspect ratio within the parameters of the 7' by 14' fixed screen.
Second, somewhere along the way I read that SMPTE recommended viewing distance was approximately 2.5 times screen height. With that in mind, I began experimenting with various image heights by using the projector's 1.33x zoom function. I found that 2.5 times height seemed a tad small for my tastes---I guess I wanted a little more cinematic impact. Anyway, I finally settled on a picture height of about 64 inches, which puts the nearer seats in my theater too close according to the 2.5x standard. I have since heard differing numbers, so I may have gotten the SMPTE standard wrong in the first place. Regardless, I liked the feel of the image size I had chosen---for me it didn't seem too big. The resulting picture from my 1.33 aspect ratio projector measured 64" by 85".
Third, it wasn't long until I was wanting to maintain the 64" height when watching widescreen movies (1.85, 2.35, etc). To achieve this constant height, variable width approach, the projector's zoom was my only tool for several years. Then came DVD with its anamoprhic capabilities, followed eventually by the ISCO anamorphic lens (introduced to me through AVS forums). These two developments have made it possible for me to maintain image height while expanding the width to fill as much of my 14'screen as I dare. The limited video quality produced by the gear I now have causes me to prefer a width of no more than about 11.5 feet on 2.35 ratio material (55" by 138" with the ISCO). Not quite where I want to be, but anything larger shows too many of the weaknesses in my aging projector and in NTSC video itself.
Fourth, my experimentations along the way suggested to me that picture height, much more than width, was the factor which determined whether a particular image seemed too large. In other words, expanding the width of a fixed height image could add much cinematic impact without overwhelming the viewer. However, when the height is expanded too much (subject to individual tastes), the picture starts to feel overwhelming, i. e., uncomfortably large, regardless of width.
For me, a 64" height in any aspect ratio remains comfortable at viewing distances of 12 to 14 feet. All of this, of course, is just personal preference---you remember the crazy kid who always liked to sit on the first row of the local Bijou...yeah, it was me. http://www.avsforum.com/ubb/wink.gif
Fifth, none of this big screen size/viewing distance talk is very helpful if the video quality is not up to the challenge of cinematically large images. I am encouraged that the new projectors, processors, and high definition video sources I always hoped for are in development or starting to become reality. I wish I knew how much longer it will take to get HD DVD for instance; but, as usual, my crystal ball is fogged over. Before TOO long, though, I believe we will have affordable video technology capable of a stunning widescreen display on larger screens than we ever thought possible. It can't happen soon enough for me!
Well, Bob, I have given an overly long answer to a very short question, I know. Probably still left out something, despite my long windedness. In any event, I hope I have been clear enough for you to see where I came from and where I want to go with respect to image size and viewing distance. Very little of this may apply to anyone else, but the quest has sure been fun for me.
Have fun! http://www.avsforum.com/ubb/smile.gif