Distance from projector? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 65 Old 04-12-2019, 01:19 PM - Thread Starter
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Should the PJ be as close as possible to the screen?

Just wondering if it matters how far away the PJ is from the screen? Should it be as close as possible or as far as possible?
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post #2 of 65 Old 04-12-2019, 03:43 PM
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Placing the projector too close to the screen may cause hot spotting, especially if you have a big screen and you have to zoom up to fill said screen.
It depends on the screen too and what gain it is.
And no, it doesn't have to be close as possible, but setting it to far back can also have the opposite affect, even more so with anything above 140 inches, it may not be bright enough.
Your question is pretty general to give you a definite answer.
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post #3 of 65 Old 04-15-2019, 10:06 AM
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The expert answer is 'No'.

This is mostly due to the fact that sharpness of a well built lens will be best when the projector is further from the screen. You are using less of the optics and will generally be using more of the sweet spot of the optics to get best image quality. This can help contrast as well.

But, in reality, if the lens is really well built, then image quality will remain close to the same throughout the zoom range, and as you move the projector closer, you get higher brightness out of lens (because you are using more of it!). This can be a 20%+ boost in brightness from one end of the zoom range to the other. So, with a larger screen, this can be a huge benefit.

Hot-spotting is not an issue I would worry much about with any quality screen, but is a concern of higher gain screens or poorly built screens (I've seen both).

Yes, the concept that "it depends" is always applicable. But, in reality, I think "it doesn't matter much" is more appropriate as a general statement. I wouldn't lean towards the front or the back of the zoom range, but somewhere between 25% and 75% of the range. Avoid the ends of zoom. Avoid the ends of lens shift. Work towards the middle of the glass that the projector has, and if you do have a larger screen, then work the projector forwards if you can. If you have a more traditional size (120" or so) then more towards the back.

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post #4 of 65 Old 04-15-2019, 11:32 AM
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Everything is a compromise.. You are going to have a range where you can get your screen size so you put it in the center of the range "If you can" other wise you put it where it needs to go ..
For example.. you want it sitting on a cabinet in the back of the room because that makes the most sense for your room but it is Near max Zoom to get the screen size.. You will get the image you get and the projector is where you need it to be..

If you can center it within the zoom range, otherwise put it where it needs to go.

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post #5 of 65 Old 04-18-2019, 04:25 AM
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All the above applies unless you want to use the zoom to vary the size of your image. Then you need to set it at a point that fill your screen for the largest image you would ever want and then has the range to zoom to the smallest size you want. Likewise the vertical offset has to cover the drop needed as the image gets smaller. Projectors with power memory for zoom,offset,focus work best for this.

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post #6 of 65 Old 04-20-2019, 11:09 AM - Thread Starter
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Screen distance for 4k.

I was able to move my couch forward. It is now 15.5ft away from my screen. Will i notice a difference between 4k and 1080p? Some people were telling me that at 17ft away i wouldnt see a difference in 4k over 1080p. Thats as far as i can go and the screen is close to being too big with this new distance.
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post #7 of 65 Old 04-20-2019, 11:12 AM
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You may notice a slight difference if viewing a 2.35/CIH screen and using the Zoom method, depending on your screen size.

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Last edited by coderguy; 04-20-2019 at 12:30 PM.
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post #8 of 65 Old 04-20-2019, 11:15 AM
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post #9 of 65 Old 04-20-2019, 11:50 AM - Thread Starter
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Sorry my screen is 135"... Wouldnt it strain someones eyes to be say 10' from a 135" screen?

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post #10 of 65 Old 04-20-2019, 12:19 PM
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Quote:
Originally Posted by sound2017 View Post
Sorry my screen is 135"... Wouldnt it strain someones eyes to be say 10' from a 135" screen?
You may see some difference. You are right on the edge.

1.5x screen width is about the farthest distance I would prefer to sit for a 16:9 image, wouldn't mind being a tiny bit closer.

This comes out to about 14.5' for your screen size at 16:9.

For 2.35/CIH, I can go bigger, about 130" to 135" from 12' away is about right, but as small as 120" is fine (which is what I settled on for now).

So, 10' for 135" is too close for me on a 16:9 screen, but probably around 12' to 14' would be more optimal.
I could definitely adjust and watch 135" from 10' if I had to, but it's getting a little big for certain things.

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post #11 of 65 Old 04-20-2019, 12:23 PM - Thread Starter
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I have to admit it looks a ton closer from 17ft to 15.5ft! I am not sure my eyes could handle 12ft. Am i too close for 1080p at 15.5ft?
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post #12 of 65 Old 04-20-2019, 12:30 PM
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I wouldn't say you are too close at all, about right for most people.
You will benefit from 4k some at that distance on that screen size I believe, but the bigger issue with 4k is lack of NATIVE 4k content.

Edit
A lot of us 'old timers' tend to want bigger and bigger screens, so 15' to 16' sounds pretty close to right for most 'other' people.
There is no exact perfect seating distance, just depends.

Personally, I have trouble deciding as well, sometimes I think I am still too far back at times.

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Last edited by coderguy; 04-20-2019 at 12:43 PM.
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post #13 of 65 Old 04-20-2019, 12:42 PM - Thread Starter
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Whats the issue with lack of native 4k content?
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post #14 of 65 Old 04-20-2019, 12:44 PM
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Quote:
Originally Posted by sound2017 View Post
Whats the issue with lack of native 4k content?
I heard they often apparently remastered the 2k disk into fake 4k because it was cheaper than obtaining the original 4k or 8k masters and remastering the entire thing from scratch.
There is a lot of Fake 4k out there, but you'll find native stuff anyhow, Planet Earth II I think, and there are others.

There are movies as well, it's just limiting and they tend to be expensive to buy in 4k format.

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post #15 of 65 Old 04-20-2019, 12:48 PM
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I sit about 10 feet from a 110" screen and it feels just about right most times, and at other times a bit too big.
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post #16 of 65 Old 04-20-2019, 12:52 PM
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Sounds about right, I have a recliner I can move closer so my seating distance varies between about 9' and 11', this is for a 106" 16:9 and 120" 2.35.

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post #17 of 65 Old 04-20-2019, 01:02 PM
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I'm at 10' from my 125" 2.35:1 screen and I can tell a noticeable difference. The first time I watched a 1080p movie then popped in the 4k disc was like DVD to Blu-ray all over again.
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post #18 of 65 Old 04-20-2019, 01:04 PM
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Quote:
Originally Posted by jedi1982 View Post
I'm at 10' from my 125" 2.35:1 screen and I can tell a noticeable difference. The first time I watched a 1080p movie then popped in the 4k disc was like DVD to Blu-ray all over again.
Yah that's pretty close, the CIH makes it easier to notice a difference because we lose sharpness from the CIH zoom method.

People can test the 'can I tell a difference' theory somewhat by making the image smaller temporarily on a regular 1080p projector.
If you temporarily make the image just 20% to 30% smaller and it appears 'significantly sharper' (not just a tiny bit), the chances are you'll see an improvement from 4k.

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post #19 of 65 Old 04-20-2019, 01:23 PM - Thread Starter
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Am i too close to my 1080p at 15.5" I have the BenQ HT2050.
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post #20 of 65 Old 04-20-2019, 02:41 PM - Thread Starter
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What is the 2.35:1 screen? Can i change it on my remote?
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post #21 of 65 Old 04-20-2019, 02:45 PM
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What we mean by CIH is an actual wide scope screen. It is a wider aspect ratio like you see at the movie theaters.
When a movie comes on (unlike most TV shows which are 16:9), a wider aspect is used so you get black bars.

CIH / Scope / 2.35 it all means the same basic thing, just different ways of saying the same thing.

Some buy a scope screen and live with side bars only on 16:9 content, some have 16:9 screens and live with the bars above/below.
Some create masking out of Triple Black Velvet and cardboard and live with a smaller CIH view on their 16:9 screen (but it gets rid of the bars), some do a combination.

Personally, I use 2 screens, one flat screen on the wall made out of blackout cloth, and one dropdown 16:9 screen (see video below for demonstration).
The JVC's have lens memory to assist this.

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post #22 of 65 Old 04-21-2019, 06:49 AM
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Sony recommends 1.5 x the image height for 4K. That's like the back row in an IMAX theatre.

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post #23 of 65 Old 04-21-2019, 07:22 AM
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We're at 10'-4" back from a 100" 16:9 screen. 1080p looks great as does 4K, but we can tell the difference between 1080p and 4K on identical material.

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post #24 of 65 Old 04-21-2019, 08:56 AM
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Quote:
Originally Posted by coderguy View Post
You may see some difference. You are right on the edge.

1.5x screen width is about the farthest distance I would prefer to sit for a 16:9 image, wouldn't mind being a tiny bit closer.

This comes out to about 14.5' for your screen size at 16:9.

For 2.35/CIH, I can go bigger, about 130" to 135" from 12' away is about right, but as small as 120" is fine (which is what I settled on for now).

So, 10' for 135" is too close for me on a 16:9 screen, but probably around 12' to 14' would be more optimal.
I could definitely adjust and watch 135" from 10' if I had to, but it's getting a little big for certain things.
I believe 1.5x screen height, not width, is the most common recommendation
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post #25 of 65 Old 04-21-2019, 09:08 AM
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Originally Posted by gravi View Post
I believe 1.5x screen height, not width, is the most common recommendation
Nope, that would be way too close. That means for a 110" 16:9 you would be sitting 6.75' away.
That's way too close. 1.5x screen width would be 12' away.

1.5x screen width is at the farthest distance I would generally like to sit, not bad but wouldn't mind being a foot or two closer generally speaking.

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post #26 of 65 Old 04-21-2019, 09:13 AM
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Quote:
Originally Posted by Gary Lightfoot View Post
Sony recommends 1.5 x the image height for 4K. That's like the back row in an IMAX theatre.
Maybe for Imax format, not for 16:9...
That's way too close for 16:9.

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post #27 of 65 Old 04-21-2019, 10:59 AM
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Quote:
Originally Posted by coderguy View Post
Maybe for Imax format, not for 16:9...
That's way too close for 16:9.
Sorry, I think it is 2x screen height. I do remember the recommendation as a function of screen height somehow. But I could be wrong.
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post #28 of 65 Old 04-21-2019, 11:53 AM
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Quote:
Originally Posted by gravi View Post
Sorry, I think it is 2x screen height. I do remember the recommendation as a function of screen height somehow. But I could be wrong.
Most of us in here have gone by recommending at least 1.5x screen width as the farthest seating position for 16:9, never height.
2x screen height would be 9' for a 110", that's still too close for most people. It might work for some, but for most it would be too close.

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post #29 of 65 Old 04-21-2019, 01:32 PM
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I’m 10.5ft from my 100” screen, I’m sure I could go a little closer but I personally think this is my sweet spot.
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post #30 of 65 Old 04-21-2019, 01:57 PM
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THX have been recommending 2.4xSH for scope since the 80s - that gives you a horizontal viewing angle of around 52 degrees for scope and 40 degrees for 16:9 when viewed from the same seat. 36 degrees, or 3.68xSH is where they recommend the back row should be, with 26 degrees as the furthest acceptable.

SMPTE recommend 2 to 4xSH which usually equates to 3xSH plus or minus one screen height as per CEDIA CEB23 guidelines.

IMAX say they have a horizontal viewing angle for around 70 degrees in their theatres, but that's more for the front or middle row, and the back row is usually around the 1.5xSH range - same as Sony's recommendation for 4K.

If you have a 16:9 screen and view it from 1.5xSH scope movies are at around 2xSH, so if you run a CIH set up with scope being 2xSH and keep 16:9, 2.20:1. 2.0:1 etc as constant image height and sit at 2xSH, you can remove the top and bottom masking for IMAX presentations/aspect changing movies to achieve a similar IMAX experience with respect to visual immersion/image on the retina.

A few people here do sit at 2xSH but as the deciding factor for prolonged comfortable viewing is the screen height, you have to ensure the top of the screen is not too high so that you are looking up - the guidelines recommend that to be no more than 15 degrees with 35 being the max acceptable. Physically looking up causes discomfort.

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