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Discussion Starter · #1 ·
A number of forum members have discussed optimal viewing distances and how this relates to screen size and resolution in one way or another. So, I put together a table that crosses up horizontal resolution with screen size and gives optimal viewing distance. In the following table the first column gives the horizontal resolution, the first row gives the diagonal screen size (for a 16:9 set) in inches. The matrix gives the optimal viewing distance in feet for that screen size and resolution. For example, a 40" screen with 1200 lines horizontal resolution has an optimal viewing distance of 8.3 feet. Any closer and your brain is capable of percieving a higher resolution and any further away your brain is only capable of perceiving a lower resolution. I used Dean Roddey's information in one of his posts where he stated
Quote:
The human visual system (at its best near the center of the fovea) has a spatial resolution of about 1 arcminute (1/60th of a degree.)

Code:
Code:
16:9    34    38    40    46    53    56    61    65    73
700   12.1  13.6  14.3  16.4  18.9  20.0  21.8  23.2  26.0
800   10.6  11.9  12.5  14.4  16.5  17.5  19.0  20.3  22.8
900    9.4  10.5  11.1  12.8  14.7  15.5  16.9  18.0  20.3
1000   8.5   9.5  10.0  11.5  13.2  14.0  15.2  16.2  18.2
1100   7.7   8.6   9.1  10.4  12.0  12.7  13.8  14.8  16.6
1200   7.1   7.9   8.3   9.6  11.0  11.7  12.7  13.5  15.2
1300   6.5   7.3   7.7   8.8  10.2  10.8  11.7  12.5  14.0
1400   6.1   6.8   7.1   8.2   9.5  10.0  10.9  11.6  13.0
1500   5.7   6.3   6.7   7.7   8.8   9.3  10.2  10.8  12.2
1600   5.3   5.9   6.2   7.2   8.3   8.7   9.5  10.1  11.4
1700   5.0   5.6   5.9   6.8   7.8   8.2   9.0   9.5  10.7
1800   4.7   5.3   5.5   6.4   7.4   7.8   8.5   9.0  10.1
1900   4.5   5.0   5.3   6.0   7.0   7.4   8.0   8.5   9.6
1920   4.4   4.9   5.2   6.0   6.9   7.3   7.9   8.5   9.5

[This message has been edited by AtlPaul (edited 03-23-2001).]
 

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Actually, that's not the only consideration. There is also how much field of view is filled by the image.


In that particular thread, I was just saying that, beyond a point, its doing you no good to have more resolution since you won't see it anyway. However, its fine to sit closer than that in order to get more of your field of view filled. So, going by your table, if you have the ubiquitous 65" RPTV, and sit that the common 12' away, then the 1200 to 1300 lines or so of horizontal resolution that it will likely provide is probably just about right (i.e. just about what you'd be able to resolve from there anyway.)


Also, keep in mind that the arcminute value is kind of a 'best of breed' number. I'm sure most of us aren't nearly that good, so the numbers would have to be brought down a bit. It would be interesting to have another table at 2 arcminutes, to see what the difference is. Also, it would be nice to take it out about 90" wide, which many FP systems reach. My relatively smallish 92" diagonal is about 78" wide, so its beyond your table.


Anyway, its interesting. I wonder if anyone believes that they have evidence to contradict these numbers.



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Dean Roddey

The CIDLib C++ Frameworks

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Oh, and of course I forgot to mention that the other concern is not to sit so close that you see line structure (or pixel structure if you've gone digital.) For NTSC material, even doubled, if you sit close enough to get a good panoramic view, you pretty much guaranteed to see screen structure (and if you don't, you should be betting your set focused.) With HD material, this shouldn't be a problem, and you can sit considerably closer. In that case, you aren't worried about the fact that you could potentially see more detail than your display can provide you. The numbers in the table would be more of a guide to place yourself such that you can at least see what's being provided.



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Dean Roddey

The CIDLib C++ Frameworks

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www.charmedquark.com
 

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Interesting material. I wonder if there's anyone that could pipe some resolution test patterns into their system(s) and try viewing at various distances? ;-) Also wonder how practical it would be to capture such screen images with a camera, perhaps with a zoom lens. Such images, IMO, would greatly aid the value of new-display reviews. -- John


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STOP DVI/HDCP AND DFAST
 

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Discussion Starter · #5 ·
Dean Roddey said:
Quote:
Actually, that's not the only consideration. There is also how much field of view is filled by the image.
I couldn't agree more! I should not have used "optimal" or at least made it explicitly clear it is only in direct relation to the mentioned factors.


In any case, along the lines of what you mentioned, I considered a 53" (4:3) versus a 36" (4:3) amongst others and ended up with the 36" because I didn't like having to look back and forth across the picture on the 53". I was missing some of the material that I would otherwise "catch" with a smaller screen at my viewing distance. But now I kind of want a 16:9 set as well. Oh, the drama! Maybe what I think I "need" is my own showroom at home - yea, like that's gonna happen! :)
 

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Quote:
Originally posted by AtlPaul:
In any case, along the lines of what you mentioned, I considered a 53" (4:3) versus a 36" (4:3) amongst others and ended up with the 36" because I didn't like having to look back and forth across the picture on the 53". I was missing some of the material that I would otherwise "catch" with a smaller screen at my viewing distance.
I don't know about this. :) Aren't films made with the idea that the movie viewer will have to move their eyes while watching the movie? Allowing the director to introduce information on the frame from planned angles?


John
 

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I think that personal preference need to be taken into account. Some of the members set 10' away from 65" screens and love it. Others of us would be driven to distraction when setting this close to this size screen. I don't say one is right and the other is wrong, just differences in the way that folks like to view things.




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Russ
 

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I dunno. At the risk of sounding condescending, I find this usually have to chalk this kind of feeling up to lack of experience. How could anyone not see that one of the major ideas of home theater is the 'theater' part? The whole point is to get a large enough screen to fill your peripheral vision, which is exactly how the real world works. Do you wear blinders when you go outside? Do you walk around jerking your head from side to side when you go outside, because there are things there that you can't see directly? Probably not. Since major aspect of the home theater world is to try more and more to recreate a real experience, having the image fill your field of view is a very important thing.



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Dean Roddey

The CIDLib C++ Frameworks

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Discussion Starter · #9 ·
Well Dean, I just guess you can chalk it up to personal preference. I know I'm certainly not going to make a big deal out of this.
 

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At the risk of saying something I don't have the data to back up...


Data already exists on viewing distance as a function of screen size for both HD and SD images. The ATTC (Advanced Television Test Center) allowed viewers to move their chairs and sit where they wanted for various HD images. This either determined or confirmed (I don't remember which) the DTV recommended viewing distance at 3x picture height. The data exists somewhere, perhaps someone can post the location.


For SD (NTSC) viewing distance, they came up with 9 feet (almost regardless of screen size.) This became known as the "Lechner Distance" after consultant Bernie Lechner. Of course, the Europeans had to do their own tests. Their answer: 3 meters!
 

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This is one of those perennial topics, and everyone's got a spin on it, including me...


For me, the ideal would be to create the field of view I get when sitting in the the middle rows of a real movie theater watching film. I'd have to be sitting just a few feet from my 55" Mits RPTV to get that, which is beyond the limitations of my set's HD resolution. Also, at that point the severe angle from the very top & bottom of the screen to my eye is so severe that only the middle band is properly illuminated.


So, since I can't get as close as I want, my rule of thumb is to get as close as I can without seeing line structure, and the screen is still uniformly lit. To my subjective eye, that seems to be about 9' for 480p DVDs, and 7' for HD on my finely focused & converged 55".


Dave
 

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I find this thread interesting as just last night I was experimenting with seating positions in the living room while watching the Sopranos in HD. My direct view set only has a 32" screen size and, from a distance of 5 or 6 feet (where the sofa is) a lot of detail normally associated with a hi def picture is seemingly "lost." But when I moved within 3 feet of the screen, I suddenly started seeing all kinds of picture detail worthy of what I would term "hi-def." I'm not sure if what I am experiencing is just a function of the limitations of the set (SONY 32XBR400) or what. I do have new glasses, so that's not it. But it certainly seems true that HD can be viewed from very close up and, in the case of this set, the closer the better!
 

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About a year and a half ago, Home Theater Magazine had a very thorough article on all aspects of constructing a home theater room or section of your house. One of the sections spoke to proper screen size, which was first based on where you plan to place your primary seating. This first takes into consideration your room size, rear and/or side speaker type, placement, and size, e.g. monopole direct radiating; bipoles, or dipoles can impact your seating location. After you know or estimate the layout of all your speakers (including your sub or subs), coupled with the size of your room, measure the distance from the estimated screen location to your seating, then...


If you have a 16:9 HDTV, the diagonal would be 0.619 times the seating distance, e.g. if you sit 10 feet away from the screen, then you would need a 6.19 foot (approx. 74 inch) screen size. Since my seating distance was about 9 foot, and I planned to mostly watch progressive scan DVDs and true hi-def programming, I then went and purchased a Mits 65 inch HDTV (0.619 x 9 = 5.511 feet x 12 = approx. 66.852 inch screen size).


This screen size has definitely worked for me at my 9 foot seating distance.


P.S. I do not think that I am stepping on any copyright issues, since I mention the source, and this Home Theater Magazine article was meant to educate anyone wanting more info on home theater construction.



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Don Silinski


[This message has been edited by donsil (edited 03-28-2001).]
 

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I'd have to agree that it is a matter of personal preference. Some people like to sit 1/3 of the way back in the theater, some 1/2 way, and some 2/3 of the way back. Some may even prefer sitter closer (or further away). I personally prefer sitting 1/2 to 2/3 of the way back -- on a few occasions the theater has been so crowded that I ended up in the first few rows and found the experience unpleasant.
 
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