# screen distance to seating

Discussion in 'Home Theater Projects' started by russell>b, Jan 29, 2004.

1. ### russell>b Auditioning

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Ok .. I have searched and done lots of reading and I keep finding 2 common forumals for working out how close you can put seating to your screen or more importnantly whats the biggest screen you can put in

the 2 formuals I keep coming across are:

closest seat can be 1.5 x screen width
closest seat can be 2 x screen width

OK so which is correct or are there different views on this ?

I aslo came accross recommended THX viewing distance which seems closer than normal ?

thanks

2. ### SteveLeach Stunt Coordinator

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I got all of the following from the web, sorry I don't remember where.

If you know the viewing distance then you can determine the proper screen size by using this calculation:
(ViewingDistance*.2679)*2 = ScreenWidth (30 degree viewing angle per SMPTE)
(ViewingDistance*.3249)*2 = ScreenWidth (36 degree viewing angle per THX)

If you know the ScreenSize then you can determine the proper viewing distance by using this calculation:
((ScreenWidth/2)/.2679) = ViewingDistance (30 degree viewing angle per SMPTE)
((ScreenWidth/2)/.3249) = ViewingDistance (36 degree viewing angle per THX)

Hope this helps

3. ### MikeWh Second Unit

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IMHO, neither is correct. Unfortunately, there is no "proper" viewing distance, because there are several variables that impact your particular circumstances. The 1.5x and 2x "standards" are only starting places.... generalizations. My recommendation is to start here:

Use this to start playing with some numbers. Then use this information to take into consideration some of the other common variables:
1. Are you planning on more than one row of seats?
2. What will be the worst viewing angle in the HT (from the worst seat)?
3. What's your personal preference; e.g., do you prefer a more immersive movie experience (by being closer to the screen)? I think this is a particularly important factor, as some people couldn't care at all about the THX or SMPTE numbers... they simply know what they like.... and after sitting at a 40-deg viewing angle, that's just what they prefer!
4. Are there published recommendations re: viewing distances for the specific pj you are interested in?? I've noticed that as the quality of "decent quality" pjs has been going up, expectations for PQ is getting higher, as well.... A major impact of this is that people are becoming more and more critical (and therefore less tolerant) of the common pj artifacts: screen door, rainbows, vertical banding, etc. The screen door problem is particularly affected by viewing distance-- I rarely see a review of an LCD projector now, without some comments related to how far you have to be for screen door to be unnoticeable.

There are other variables... I'm sure others will be happy to add to these.

4. ### JayPo Stunt Coordinator

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Just a quick question, when you say:

Is that angle measuring vertically (how high the screen is) or horizontally (how far you can sit to the side)?

Thanks.
JP

5. ### MikeWh Second Unit

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It's actually neither.

Click on the link I provided, and the graphic there describes what I meant-- the horizontal angle subtended by the complete width of the screen at a given viewing distance. BTW, "40 degrees" was meant to be an arbitrary reference, just as an example. There was a thread here about 6-9 months ago, where a few people mentioned how they like to be close enough to the screen, so that they felt immersed in the picture (almost like an IMAX experience). They were talking upwards of 40-50° horizontal viewing angle, as I recall.

The point I was trying to make is-- do what looks good to you! The best advice I can give on this is:

1) Go to an HT meet in your area or check out a audio/video store's setup, so you can see what it's like at various screen sizes and viewing distances.

2) Tape paper or poster boards to your wall, suggesting the screen size you think you'll like. Move a chair around the room at various distances and angles. Just remember that if you are not using your final HT seats, you might be viewing from different vertical viewing angles, which may effect the experience for you. Also take into consideration that most people don't have just one seat in their HT. You may need to compromise between the perfect sweet spot and getting a good enough picture from the worst seats.

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7. ### Tom Jr Extra

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I know I'm new around here, but here's something I did, just for reference:

8. ### JayPo Stunt Coordinator

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Tom ... I'll have to try that.

Mike ... thanks for the info.

9. ### MikeWh Second Unit

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Tom-- I'm glad you mentioned that, because I started to do this once, until I noticed the people sitting down the row looking at me in a strange way.

I'll have to just bite the bullet and actually do the measurements, but what I'm guessing is that I actually prefer two different experiences. I think I'd actually prefer a greater horizontal field of view (HFOV) in an HT than at the movies. I'm not sure though. I'll have to take a protractor to the movies next time.

If it is actually true (and not just a perception), then I'm guessing it's due to the VFOV: to get a larger HFOV, I'd have to sit up closer; unfortunately, that causes me to crane my neck more.

10. ### SteveLeach Stunt Coordinator

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There is a similar test for vertical field of viewing that I heard about.

It starts the same, go to your favorite theater, sit in your favorite spot, close one eve, extend one arm out in front of you. Get maximum extension between the tips of your thumb and little finger. Line up the top of your thumb with the top of the screen. The see where the bottom of the screen is in relation to the tip of your little finger. For me, the tips of my thumb and little finger line up with the top and bottom of the screen.

Now in your home, sit in your sweet spot and do the same thing. Have someone draw lines on your viewing wall for the top and bottom edge of the screen.

You now know how tall your screen should be, next using the 9x16 or 3x4 ratio you can determine how wide the screen should be in relation to it's height.

After I did all of that, it was pretty close to the formulas I mentioned above. But as others have stated, it's what you like that matters.

Don't worry, everyone in the theater looks at me weird when I did that test too.

enjoy...

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