16:9 Screen Vs. 2.37:1 CIH Screen

[maikeldepotter]

Mark Techer wrote:

The HD panel is 1920 x 1080. When you zoom, you only see 1920 x 810 with the remainder being projected off the top and bottom. As you zoom, the pixels increase both horizontally and vertically.

Adding an anamorphic lens allows your projected image to be made from the entire panel instead of just 75%. The lens expands the pixels, but only in the horizontal direction, so the vertical size remains the same. This is benificial as we are more sensitive to vertical than we are to horizontal pixel structure...

Mark

Thanks for your reply Mark. I understand what you are saying. The question remains what the maximum viewing distance should be to actually benefit from this improved vertical pixel structure. On a 2 meter wide screen the pixels measure 1x1 mm. Even from the the shortest recommended viewing distance of 1,45 meter (field of view 140 degrees) I am not able to see any pixels. Maybe you can still see a difference in sharpness? I really don't know . Has anyone experienced this in a side-to-side comparison: "Zooming out" versus "Anamorhpic projection" with a HD beamer at different viewing distances?

[Mark Techer]

Acually you should work your seating distance from image height, not the width, where you should be no closer than 2x the image height and no farther back then 4x.

The beauty of CIH with a lens is that those pixels stay the same size (vertically) as you change ARs, so you do not loose sharpness*.

*pending the type of lens.

When you zoom, your pixels do increase vertically, so it is almost like going back from 1080 to 720, but not quiet, it is actually about 810...

Mark

[maikeldepotter]

Mark Techer wrote:

Acually you should work your seating distance from image height, not the width, where you should be no closer than 2x the image height and no farther back then 4x.

The beauty of CIH with a lens is that those pixels stay the same size (vertically) as you change ARs, so you do not loose sharpness*.

*pending the type of lens.

When you zoom, your pixels do increase vertically, so it is almost like going back from 1080 to 720, but not quiet, it is actually about 810...

Mark

In my set-up the viewing distance is 3x the image height using 2.37:1 projection (34 inch high; 80 inch wide), and 2.5x the image height using 16:9 projection (41 inch high; 73.5 inch wide).

So I don't have real CIH projection (constant image height). But in this way I keep the bottom of the projection at the same height (measured from the floor 31 inch) when going from one format to the other just by zooming. I have a variable masking screen that allows me to horizontally adjust the projection surface by pushing one button on the remote.

In this way I believe I have created close to optimal viewing distances (according toTHX and SMPT standards) for both 2.37:1 and 16:9 formats. And yes, I understand I am not using the projector's full resolution capability with 2.37:1.

But again, will the picture quality visibly improve with an anamorphic lens?

Will the added sharpness be more predominant than the possible adverse effects of lens imperfections and faults introduced by the pixel recalculations for the vertical stretching of the 2.37:1 picture to fit the 16:9 LCD chip?

I am not a disbeliever. I just don't know!

[Prof.]

maikeldepotter wrote:

But again, will the picture quality visibly improve with an anamorphic lens?

On a 2 Metre.. wide screen with an HD system....There will be some improvement but probably barely noticeable..
If you had a 3 Metre wide screen, then there would be some obvious improvement over the zoom method..

Will the added sharpness be more predominant than the possible adverse effects of lens imperfections and faults introduced by the pixel recalculations for the vertical stretching of the 2.37:1 picture to fit the 16:9 LCD chip?

As far as I'm aware..it would not be an issue..

[Prof.]

Just to add to that...

The whole idea of having a Scope setup is not just to remove the black bars, but to have that very wide screen image...Like you see in the Cinema...that really immerses you in the action on the screen..

It is generally accepted that the minimum width for a scope screen is 8' wide, with 9' being ideal if your room is large enough..
Anything smaller is not going to give you the same effect, and if 2 Metres is your maximum size you are able to fit or have in the room..then it probably isn't worth the additional costs involved..

[Mark Techer]

maikeldepotter wrote:

But again, will the picture quality visibly improve with an anamorphic lens?

Absolutely, becuase with a lens, your vertical pixel size remains the same for all ARs as does the useage.

The image you see is made up of by the total (X) number of pixels on the panel, so why not max them all the time - a lens will let you do that, where zooming can not becuase you throw at least 25% of the vertical rez away.

If you have a 1080 projector and CIH, when watching 16:9 you have 1080 vertical pixels being used, and when watching Scope using the lens, you will also have 1080 vertical pixels being used. The best way to describe the CIH image is "dense", but in the end, seeing is believing...

Mark

[maikeldepotter]

Prof. wrote:

Just to add to that...

The whole idea of having a Scope setup is not just to remove the black bars, but to have that very wide screen image...Like you see in the Cinema...that really immerses you in the action on the screen..

It is generally accepted that the minimum width for a scope screen is 8' wide, with 9' being ideal if your room is large enough..
Anything smaller is not going to give you the same effect, and if 2 Metres is your maximum size you are able to fit or have in the room..then it probably isn't worth the additional costs involved..

Your are stepping on my soul Prof! Putting so much time and effort in building my dream HT and now hearing that my screen is too small to ever reach the Cinema feeling....

But seriously, does the immersive feeling not more depend on the actual viewing angle (viewing distance : screen height ratio), than solely on the screen width? If I am sitting on the last row of a Cinema with a huge screen I have a much lesser immersive feeling than sitting 2,5 metre away from my 2 metre wide screen.

Could the generally accepted minimum width of 8' has to do with the assumption that you are not building your HT for just one or two people (little place within optimal viewing boundaries)? Because that is what I have done.

The other possibility I can think of is that there exists someting like a minimal viewing distance in order not to put too much strain on your eyes to focus on the screen. I just never heard or read about such a phenomenon. Am curious though if anyone has more info on this, or other factors that influence the immersive sensation we are talking about here.

[Mark Techer]

maikeldepotter wrote:

But seriously, does the immersive feeling not more depend on the actual viewing angle (viewing distance : screen height ratio), than solely on the screen width? If I am sitting on the last row of a Cinema with a huge screen I have a much lesser immersive feeling than sitting 2,5 metre away from my 2 metre wide screen.

This is correct and why I am happy watching scope on a 2.4m wide screen the same as watching scope on a 3.5m wide screen. If your seated between 2x and 3x the image height, screen size has no real bearing...

Could the generally accepted minimum width of 8' has to do with the assumption that you are not building your HT for just one or two people (little place within optimal viewing boundaries)? Because that is what I have done.

an 8' screen Scope screen is still a good height. If your screen gets to narrow, then you might not ecperience the "big screen" effect, but as I said above, seating distances still apply here...

The other possibility I can think of is that there exists someting like a minimal viewing distance in order not to put too much strain on your eyes to focus on the screen. I just never heard or read about such a phenomenon. Am curious though if anyone has more info on this, or other factors that influence the immersive sensation we are talking about here.

2x the image height is the minimum and 4x the maximum. The so called "Preferred Angle of 36 degrees" is the same as 3.68x the image height...

Mark

[maikeldepotter]

Mark Techer wrote:

This is correct and why I am happy watching scope on a 2.4m wide screen the same as watching scope on a 3.5m wide screen. If your seated between 2x and 3x the image height, screen size has no real bearing...

Thanks Mark, that is the answer I was hoping for with my "only" 2.03m wide screen.

Mark Techer wrote:

2x the image height is the minimum and 4x the maximum. The so called "Preferred Angle of 36 degrees" is the same as 3.68x the image height...

OK, that's an easy one to remember: 36 degrees = 3.7x the image height (personally I like to sit closer to the screen, at about 2.8x to 3x).

Now, the issue I wanted to put forward is this:

If the "preferred" seating distance is 3.7 x the image height, I can theoretically have a "immersed" sensation looking at a 10 inch wide high resolution screen at a viewing distance of 15.5 inch. However, the focus effort for my eyes wil will be like reading a book . This is a different feeling than staring into a distance like in a very big cinema .

The question I want to put to the forum is:

Does the viewing distance and resulting focus effort for your eyes has a significant impact on the movie viewing experience, especially with regard to the "immersed feeling" effect. I think it does not. Please comment

PS Yes, I like Smilies.

[Mark Techer]

What you will find is that your eyes will probably strain more watching HD on PC monitor at 3x the image height than watching the same program on a screen that is over 2m tall. In this case, it not the size of the image, but the distance to the image that must be taken into account. I think you will find however that the "immersion" is reduced becuase the smaller screen size, but your field of view (what you actually see) should be about the same.

Hope that makes sense...

Mark

[Prof.]

maikeldepotter wrote:

Could the generally accepted minimum width of 8' has to do with the assumption that you are not building your HT for just one or two people (little place within optimal viewing boundaries)? Because that is what I have done.

Maikel...Sorry if I quashed your ideas on the screen size..

It's a bit like TV sizes...You buy a 36" tv and put it in your living room and it looks big!!..
Then after some time you start to think "this tv is not all that big, I think I need to get a 42" screen"..

And that's how it goes with projection screens as well..

I built my theatre for just me! (I'm a free man) and I made an 8' wide Scope screen..
When I first projected onto it with the anamorphic set up, it looked BIG!!...I sit 9'6" from the screen..
Now after just 6 months..It's not looking so big!

I'm about to make up a new screen, using a different finish than my current screen, and I'm tempted to make it even bigger, in fact another foot wider!!...
Do you see my point?

I can practically guarantee you that if you go with an anamorphic set up, you will not be happy for very long with a 2 Metre wide screen...

[maikeldepotter]

Prof. wrote:

Maikel...Sorry if I quashed your ideas on the screen size..

It's a bit like TV sizes...You buy a 36" tv and put it in your living room and it looks big!!..
Then after some time you start to think "this tv is not all that big, I think I need to get a 42" screen"..

And that's how it goes with projection screens as well..

I built my theatre for just me! (I'm a free man) and I made an 8' wide Scope screen..
When I first projected onto it with the anamorphic set up, it looked BIG!!...I sit 9'6" from the screen..
Now after just 6 months..It's not looking so big!

I'm about to make up a new screen, using a different finish than my current screen, and I'm tempted to make it even bigger, in fact another foot wider!!...
Do you see my point?

I can practically guarantee you that if you go with an anamorphic set up, you will not be happy for very long with a 2 Metre wide screen...

I see you point Prof. I am convinced In the end it all comes down to the same conclusion: Size does matter, the bigger the better!

Thus, when creating your HT you should try to make the screen as big as your possibilities permit (room and financial wise). Since we are talking about Home Cinema on this forum, let's say the maximum height you can achieve is 8' (2.45m), resulting in a maximum screen width of 19' (5.80m) . Your minimum viewing distance lies around 16' (4.9m).

So if you have a room of measuring 20'x20' (6mx6m) or more, why stick to a procliamed ideal 9', and not go for 19' wide?

[Mark Techer]

Since we are talking about Home Cinema on this forum, let's say the maximum height you can achieve is 8' (2.45m), resulting in a maximum screen width of 19' (5.80m) . Your minimum viewing distance lies around 16' (4.9m).

Yes, 2x the image height is the closest you want to be regardless of screen size with 3x being preferred...

So if you have a room of measuring 20'x20' (6mx6m) or more, why stick to a procliamed ideal 9', and not go for 19' wide?

Because 12 feet wide is about the largest you can have in a 20 foot deep room.

Formula is -
20 / 3.68 x 2.37 = 12.88

Mark

[maikeldepotter]

Mark Techer wrote:

Because 12 feet wide is about the largest you can have in a 20 foot deep room.

Formula is -
20 / 3.68 x 2.37 = 12.88

Mark

Thanks for pointing this out Mark. So, the ideal HT room measures 20' (6m) wide and 30' (9m) deep, permitting a 19' wide screen. Am I right?

PS I am just trying to get things really clear here, not only for the theoretical sake. I have friend who is buiding a new house and I like to give him the best advice on how to prepare his own HT.

[Mark Techer]

maikeldepotter wrote:

Thanks for pointing this out Mark. So, the ideal HT room measures 20' (6m) wide and 30' (9m) deep, permitting a 19' wide screen. Am I right?

Actually the ideal room also requires careful consideration for room acoustics as well.

For example, a room's length should never be greater than 3x times the height, which is why you see room ratios like 1.0:1.6:2.3.

Then you still have to take the screen height saeating distance into account...

Mark

[maikeldepotter]

Mark Techer wrote:

Actually the ideal room also requires careful consideration for room acoustics as well.

For example, a room's length should never be greater than 3x times the height, which is why you see room ratios like 1.0:1.6:2.3.

Then you still have to take the screen height saeating distance into account...

Mark

OK Mark, we are getting closer....

So if the maximum room height is 8' (2.45m),
the maximum room depth should be 8'x3=24' (7.3m),
the maximum screen width 24'/3.68x2.37= 15.5' (4.7m)
the corresponding screen height (at 2.37:1 projection) 6.5' (2.0m)

I then would put the screen 1.5' up from the floor.
At a viewing height of 3.5' (eye level) I will be at about 1/3 of the screen height.
Believe that's OK?

What do you think?

Maikel.

[Mark Techer]

maikeldepotter wrote:

OK Mark, we are getting closer....

So if the maximum room height is 8' (2.45m),
the maximum room depth should be 8'x3=24' (7.3m),
the maximum screen width 24'/3.68x2.37= 15.5' (4.7m)
the corresponding screen height (at 2.37:1 projection) 6.5' (2.0m)

I then would put the screen 1.5' up from the floor.
At a viewing height of 3.5' (eye level) I will be at about 1/3 of the screen height.
Believe that's OK?

What do you think?

Maikel.

I think the following would work really well (actually know this as I have built one in the past)

Room Ratio

1.0 : 1.6 : 2.3

Room Size

2445mm x 3912mm x 5624mm

Screen Size (MAX)
5624mm / 3.68 x 2.37 = 3622mm x 1528mm

Screen Size (MIN)

5624 / 5.18 x 2.37 = 2573mm x 1086mm

Seating Distances

MAX screen - Not less than 3056mm with 4584 being preferred.
MIN screen - Not less than 2172mm and not farther than 4344mm with 3258mm being preferred.

Surrounds to be at 3x image height...

Mark

PS You wil notice that even with the largest screen size there is roughly 150mm oneach side for the side masking curtains...

[muzz]

Never even considered CIH, because I also always felt that the lenses were WAY over my budget.

I now see that Mark has made this an affordable endeavor, that I may look into now.

Thanks Mark

Gary

[maikeldepotter]

Mark Techer wrote:

I think the following would work really well (actually know this as I have built one in the past)

Room Ratio

1.0 : 1.6 : 2.3

Room Size

2445mm x 3912mm x 5624mm

Screen Size (MAX)
5624mm / 3.68 x 2.37 = 3622mm x 1528mm

Screen Size (MIN)

5624 / 5.18 x 2.37 = 2573mm x 1086mm

Seating Distances

MAX screen - Not less than 3056mm with 4584 being preferred.
MIN screen - Not less than 2172mm and not farther than 4344mm with 3258mm being preferred.

Surrounds to be at 3x image height...

Mark

PS You wil notice that even with the largest screen size there is roughly 150mm oneach side for the side masking curtains...

Hi Mark,

I do not understand the 3x image height for the surrounds. Having a 9' wide and 3.8' high screen you would have to hang the surrounds 11.4' from the floor????

Maikel

[Mark Techer]

maikeldepotter wrote:

Hi Mark,

I do not understand the 3x image height for the surrounds. Having a 9' wide and 3.8' high screen you would have to hang the surrounds 11.4' from the floor????

Maikel

No 3x the image height off the screen or 90 degrees to the seating positon of 3x the imaghe height if that makes sense...

Mark

[maikeldepotter]

Mark Techer wrote:

No 3x the image height off the screen or 90 degrees to the seating positon of 3x the imaghe height if that makes sense...

Mark