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Projector throw angles

2289 Views 6 Replies 4 Participants Last post by  Bill Kentucky
Just getting to the point of being ready to purchase my projector, I'm looking at placement options and seeing what size screen I can run.
My issue is that there is a load-bearing beam in the middle of my room, off center by about 6". I would prefer to mount the projector behind the beam, as doing so in front of the beam would limit my screen size. My question is what kind of angle does a projector usually project an image from the lens? Basically, how far back can I go before the beam is interfering with the image? If I run the projector right at the back of the beam, the lens would be pretty much level with it, so that won't be an issue, but I'd like to go back another 6-12" if possible.
Picture attached to hopefully express what I'm looking for.

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I assume your talking about a post supporting the beam. You won't be able to move the projector back much. Tie a string too the left edge of the screen back to the lens of the projector and as long as it doesn't hit the post your ok. A projector with horizontal lens shift would help some moving it farther away from the post.
Just getting to the point of being ready to purchase my projector, I'm looking at placement options and seeing what size screen I can run.
My issue is that there is a load-bearing beam in the middle of my room, off center by about 6". I would prefer to mount the projector behind the beam, as doing so in front of the beam would limit my screen size. My question is what kind of angle does a projector usually project an image from the lens? Basically, how far back can I go before the beam is interfering with the image? If I run the projector right at the back of the beam, the lens would be pretty much level with it, so that won't be an issue, but I'd like to go back another 6-12" if possible.
Picture attached to hopefully express what I'm looking for.
I think you mean a post.

Basically, the light beam will expand evenly, so you can draw a line from the projector lens to either side of the screen to check if the post will interfere with the image. Be aware that there are short throw projectors that can throw large images from short distances, such as this new one, for example:
https://www.projectorcentral.com/Optoma-EH412ST-projection-calculator-pro.htm
If you have a projector with lens shift, that will give you much more placement flexibility.

A projector like the Epson 4010, 5040, or 5050 will allow you to move the projector to the right of the beam by a foot or so to give you more clearance of the beam.

You didn't actually mention several things which matter....

1. What is your screen size?
2. What is the distance from the screen to the beam?

A short throw projector will actually give you a larger image size and may be the ideal choice.

But, as mentioned, using the screen width, you can use a string, or a laser, from the projection lens location to the edge of the screen and see how far back you can go before the post is in the way. Yeah, it won't likely be very far.
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Thanks everyone for the help! I did mean a post, which is what supports the beam that runs horizontally across the ceiling.



To answer the questions:

If you have a projector with lens shift, that will give you much more placement flexibility.
I do not have a projector yet, I want to plan everything out before purchasing to make sure I buy things that will fit and work in the room. I am looking at the JVC x790r currently as my top pick though.


1. What is your screen size?
Again, nothing purchased yet, but I'm on the fence over 16:9 and 2.35:1. If I go 16:9, it will most likely be a 120" screen. If I go 2.35:1, it will be something like 127" (or whatever the equivalent is). I will be purchasing an AT screen, as I don't know if I want to try a DIY screen just yet, so whatever the standard size is.



2. What is the distance from the screen to the beam?
This isn't 100% set yet, as I still have to build the wall that my LCR will be set on, but based on my measurements the wall will be about 12' 2" from the post. The post is off-center about 6" to the left, so if I put the PJ behind the post I will have several inches before it is in the way. Looking at the calculator on the x790r, the 120" 16:9 screen will be just about perfect, the 2.35:1 screen will require the PJ to be set back another foot. The post might be my deciding factor here, I'm not sure if the lens shift will be able to make up the difference of setting it back another foot.
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Calculations get complicated since vertical shift is less the more you use horizontal shift. Here is an excellent calculator that should help a lot in figuring it out.

http://www.reviewtranslations.com/projection_calculator_en.html
Calculations get complicated since vertical shift is less the more you use horizontal shift. Here is an excellent calculator that should help a lot in figuring it out.

http://www.reviewtranslations.com/projection_calculator_en.html

That calculator gave me much different data than the one at projectorcentral. If the one you linked is correct, it looks like I'll have no issue with mounting it directly behind the post. It also looks like a 142" 2.35:1 screen will be easy to fit at the length I wanted to mount it at. I will only need a few % of vertical and horizontal shift and it looks like I'll be able to have quite a bit of flexibility with extra shift.
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