While your input can be informative, sometimes condescension can taint your message. Starting with this response to DL4567:
Originally Posted by GeorgeAB
The answer is painfully simple and embarrassingly fundamental.
Which projects the attitude: "you painfully obtuse person who hasn't grasped the simple answer, you should be embarrassed to ask this question
." (After all, why reply with the words "painful" if it doesn't portray your disdain for the question, and "embarrassingly" if you are not implying someone ought to be embarrassed by asking such a question?).
DL4567's question was fair enough. This forum is filled with enthusiasts, many quite informed and/or who are familiar with issues involved in their goal to attain excellent picture quality. And yet many are using image sizes and viewing angles that are closer than the ones you describe as "reference." That includes some reviewers, calibrators as well, as I remember (especially those employing CIH systems).
You mention this reference parameter: "A 1920 x 1080 image should generally occupy a 30 degree viewing angle for average 20/20 vision.
" But many here have noted, upon experimenting with image sizes, that excellent 1920 x 1080 is certainly not limited to that size. As I mentioned, I can watch numerous Blu-Ray sources that remain spectacularly sharp, detailed and clean at much larger viewing angles (and being able to compare the image directly with the smaller viewing angle you describe). And with no pixelation. This has been the experience of many others as well.
Yes, you may wish to point out "Well then, anyone doing this departs from the reference criteria numbers I have supplied, and I'm only talking about IF someone wants to achieve that goal.
" Ok, but the point is that it's not necessarily the general experience here that such viewing angles ARE always or ought to be the goal. Hence that goal itself is not obvious. So it CAN seem a bit weird to see super expensive theaters offering less immersive viewing experiences. Even though certain pro standards exist, it's not obvious that everyone would be, or want to be, abiding strictly to those standards, especially given the success (as owners see it) of not being tied to the viewing ratios you suggest.
Further, it's also not obvious that the professional theaters DL4567 and I are talking about ARE totally concerned with replicating a reference experience. All too often the decor choices are total head-scratchers in this regard. Be it ill-advisedly light decor choices (which as I said I see so often in many professionally-designed set ups), reflective or distracting surfaces near the screen etc. Little of which you'd ever get in any professional "reference" setting. When I've asked why these types of compromises seem to appear in so many professional installations I've sometimes been told "We would have done X or Y differently, but that's what the customer wanted." Which is understandable...but the point is that, nonetheless, a good number of professional installs I see do not actually SUGGEST they are so intensely concerned with a reference image experience. And so the assumption "the screens are of a smaller size since the goal is obviously a reference experience" isn't so "painfully" and "embarrassingly" obvious. We can't usually know from pictures precisely what the viewing angle is on the theater so the screen may look small because it was made to reference viewing angles...or it may be small as one of any number of compromises that occurred in the design process.
So, again, all this considered I think DL4567's question could have been met with language that did not strongly imply the answer is obvious and someone asking that question on this forum ought to be embarrassed.