# recommed viewing distance



## AAIERON (Oct 12, 2006)

what should be the viewing distance from a 42inch
plasma?
How do you know if you can pick up off air high def. signals?
thanx


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## annenoe (Oct 19, 2003)

Your first stop for OTA information is antennaweb.org. Click "choose an antenna" and enter your address and ZIP code. That will tell you how far and in what direction you are from the towers that broadcast your stations. It'll also generate a map that shows exactly in what direction your antenna needs to point.

Then click on any of the "color boxes" and it'll tell you what kind of antenna you'll need to get that station. You need to click on the "worst" one you want/need where "better to worse" is based on the color - you'll see what I mean when you go to antennaweb. Yellow is easiest to get - violet is hardest.

There's a pretty good chance you can receive OTA signals but start with that. In my case, I'm within 30 miles of the towers I need to receive majors, all the towers are in the same general direction from my house, all of them are "yellow", there are no major hills/mountains between me and the towers. I'm able to receive signal using an indoor antenna that only has to point in one direction. 

Others have to hoist larger antennas on their roof or attic...

That said, OTA picture quality is better than D* signal, but is also subject to intermittent failure - more so than satellite. It's all sort of 6 of one, half a dozen of an another.

But you'll be asked first what antennaweb says so you might as well do that first.


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## bpratt (Nov 20, 2004)

> but is also subject to intermittent failure - more so than satellite.


I guess that depends on what area you are in. In my area (Salt Lake City), I seldom see an OTA problem with digital broadcasts. For some reason and only occasionally, NBC will switch from a 16X9 HD picture to a 4X3 SD picture for a few minutes but the other channels never seem to have a problem.

Try this site for viewing distance:
http://www.cnet.com/4520-7874_1-5108580-2.html


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## hiker (Nov 29, 2001)

Here's another one:
Viewing Distance Calculator


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## Dssturbo1 (Feb 23, 2005)

find the model # and google it. it needs to have a built in atsc tuner for it to tune in local stations digital broadcast. 

sit where you feel comfortable. 42" plasmas are not true 720p/1080i/1080p hd displays so it is not as critical.


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## mr.unnatural (Feb 2, 2006)

Calculator? Don't need no stinkin' calculator. Minimum viewing distance is normally twice the diagonal measurement of the display. I know the math may be tough for some of you but for a 42" plasma you should sit at least 84 inches from the set or approximately 7 feet.  

This formula has always been true for standard definition sets but I would imagine you can sit a bit closer with HDTV sets. The minimum viewing distance allows you to sit at a point where the interlaced lines displayed on an NTSC set showing 525 lines blend together and disappear. If you sit any closer you can start to see the individual lines. 

Since HDTV sets have more lines per inch you should be able to sit much closer before you can detect them. Note that this generally applies only to interlaced settings like 480i or 1080i. Theoretically, you shouldn't be able to see any lines with a progressively scanned image.


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## jfelbab (Jan 18, 2002)

Crutchfield's suggested viewing distance table

http://www.crutchfieldadvisor.com/S-cGTwcAHxzKj/learningcenter/home/tv_faq.html#viewing_chart


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## TyroneShoes (Sep 6, 2004)

mr.unnatural said:


> Calculator? Don't need no stinkin' calculator. Minimum viewing distance is normally twice the diagonal measurement of the display. I know the math may be tough for some of you but for a 42" plasma you should sit at least 84 inches from the set or approximately 7 feet.
> 
> This formula has always been true for standard definition sets but I would imagine you can sit a bit closer with HDTV sets. The minimum viewing distance allows you to sit at a point where the interlaced lines displayed on an NTSC set showing 525 lines blend together and disappear. If you sit any closer you can start to see the individual lines.
> 
> Since HDTV sets have more lines per inch you should be able to sit much closer before you can detect them. Note that this generally applies only to interlaced settings like 480i or 1080i. Theoretically, you shouldn't be able to see any lines with a progressively scanned image.


While I agree with much of what you say, what theory would that be? Progressive lines and any gaps between them are just as visible as equivalent interlaced lines. The chief advantage of progressive scanning is that it minimizes motion artifacting (non-compression based), but it can't magically remove the visible gap between lines, or even ameliorate that visibility. Interlace flicker on non-CRT displays is also not a factor, as there are the equivalent number of fields per second drawn in 1080i and 720p.

If you are viewing ATSC video, and I will assume that this generally what folks will be viewing on a HDTV, it seems to make sense to sit at the distance that the entire system was actually designed for.

When the ATSC designed the system, this was the first question they considered after deciding on an aspect ratio: How practically far away should the viewer sit and how many scan lines should we then use to make them (the scan lines, not the viewers) invisible at that distance? And the answer to the distance question was 3.3 screen heights for 720p, and 3 screen heights for 1080i. This is based both on human 20/20 vision being able to discern 1/60th of a degree of arc, but nothing finer than that, as well as how many degrees of the field of view that a 16:9 screen should fill for the best experience.

That's in the specs, and you can look it up. Other arbitrary recommendations run counter to those recommendations, and will not work as well as that simple formula, because anything other than that is a compromise and does not fit the ATSC design as precisely. IOW, sit closer, and scan lines start to become visible. Sit further away, and the advantage of high resolution and wide image becomes less of an advantage.

Since both 1080 and 720 video are ubiquitous, and since not all displays are 1080-native, the general recommendation is then 3.3 screen heights, assuming you want to get the best experience out of ATSC on a HDTV. If you abhor calculators, just remember that the distance for a 42"-er using that formula is about 6.5 feet. Of course you can sit further away but as you move further away, the experience begins to degrade, and at some point not a great deal further than 6.5 feet, 720 looks just like 1080. Go very much further and 1080 won't resolve any better than 480, which kind of defeats the entire purpose of HD.

Now of course, no one needs a calculator, but they are still nice to have. No one needs HD, either, but it is also still nice to have. And the VDC above is a great tool, not only because it gives you the specific answer tailored to the screen you are considering buying (or the room you are considering placing it in), but it also gives you all of the other recommendations, such as THX, and the rest, which can give some perspective to the whole issue.


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## newsposter (Aug 18, 2002)

annenoe said:


> That said, OTA picture quality is better than D* signal, but is also subject to intermittent failure - more so than satellite.
> .


i'll disagree here also. During storms, my wife sometime says, so what are we gonna lose tonight? I pull up tivo2 and see that it's all broadcast stuff and happily tell her, it's all OTA tonight so we will get everything in. And we do. I can't recall my last OTA failure. But had tons of DTV outages this year due to storms.

and for the record i love my 8ft distance for my 57inch crt. I'd imagine you have to be a bit closer for 42


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