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Discussion Starter · #1 ·
I've been lurking around these forums for quite a while now. This is the first time I haven't been able to find an answer to my question.


I'm going to get a FP and am unsure about CIH. When I use the projection calculator for my possible future pj it says with a 2.35:1 screen I will need a different offset than with 16:9 material.


My understanding of CIH is 16:9 material will have black bars on the side and the 2.35 material will fill the whole screen. The calculator suggests that the projector will have to be two different distances from my ceiling depending on what I am watching.


Which distance should I pay attention to?


Here is an example.


The first picture shows how things would be if I used a 16:9 screen with a 45" high screen.


The second shows the same height screen but with a 2.35:1 ratio.


So, which set of numbers should I pay attention too?


The next set of questions comes up when I read how to factor in the X10's offset in relation to ceiling height.


My room dimensions are 11.5'x17'x8' so I have figured that my screen will be about 24" from the ceiling using the first set of numbers, and about 26" from the floor. This is again assuming that my screen is 45" high. With a 2.35: ratio the screen would be 105.8" wide and would give me a 115" diagonal screen. At this same height I would get a 92" diagonal screen that is 80" wide.


I'm worried that this will cause problems for the people in the second row. I just got a call that my couches are ready for me to pick up and I need to begin construction on my riser. I plan to make it about 9" high and the width of the room. The couches I got are 41" high so the back of the couch in the rear would be about 50" high and almost 4' from the ceiling. At that height people's heads would be close to the center of the screen so that should be OK. Right?


So, having thought all of this out, my screen dimensions are pretty much exactly where I want them. I'm just concerned that the x10 won't work for my room. If it will, great, but if not does anyone have any suggestions?


Thanks in advance, sorry for all of the questions.

 

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I think your idea of CIH is flawed.


For CIH, you need a lens in front of your projector. The projector itself will not give you a CIH. It will project a 1.78 image all the time, and 2.35 material will have bars top and bottom.


Now if you buy a lens, then that will be installed in front of your pj and when you watch 2.35 material, you'll tell the projector to stretch the projected image up to 1.78 (distorts the height of the image but uses the full resolution of the pj to create the picture). Then, the lens will stretch the image wider, and that will make the 2.35 image out of the 1.78 the projector is sending to the lens.


So, 16:9 material, you remove the lens.

23:9 material, you put the lens in place.


I hope that makes sense now...
 

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Discussion Starter · #4 ·
I forgot to mention that I plan on getting a lens eventually. That is why I was curious about which set of numbers to pay attention to. By what you guys are saying the numbers for the 16:9 screen are what I need to be looking at before I begin construction of my screen.


I want to build a diy screen, but would rather not paint one. Any cloth recommendations for the x10 seeing as though it has a fairly low contrast ratio. I've read on here that gray screens work best in this scenario, but haven't found a cloth or laminate that comes in decent shade of gray without painting.


any suggestions?
 

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DIY Granddad (w/help)
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The PJ calculator does not take into account the use of a CHI lens, merely the positioning of the PJ itself to effect a position for the image that does NOT require any keystone adjustments.


To effect 2.35:1 & 16:9 you'll need to employ the use of a PJ that has Lens Shift and Zoom (..both powered if at all possible...) and it would be VERY advisable to consider one that also has a "Stretch Mode" intended for use with any eventual Anamorphic Lens.


PM me for some very specific Screen suggestions, and links to where you can even get the preferred PJs and a decent but really affordable CHI Lens/Sled set-up. Include as much info and requirements/limitations yoy have for your Project then be sure to re=post again with your project's progress fr everyone to benefit from.


MMan
 
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