I'm trying to figure out as much as I can before buying parts. I've been toying with the following formula...
Projection Distance * LCD Size/Focal Length of lens = Projected Screen Size
I wanted to get this lens below, as it is adjustable for fine tuning.
proj. lens
So taking the size of my LCD(15", 381mm), the distance from where the projector will be located to the wall(7', 84", 2,133mm), and the median focal length of the projection lens above(about 223mm), I get a screen size over 140...more than double the diagonal size of what I would like.
When I move things around a bit in the formula to find out what FL I will need on my lens (in order to project a 60" screen), I get about 533mm...the longest focal length I've seen is about 455 on the long throw lens on the same site as the lens linked to above.
So my question is basically...someone double check what I'm doing here and make sure I'm not blowing it. I've searched day and night. I'm pretty sure I'm doing everything right, but obviously I'm not. Placing my projector 43" from the wall for a 60" screen just doesn't seem right.
Thanks in advance for any help.
Projection Distance * LCD Size/Focal Length of lens = Projected Screen Size
I wanted to get this lens below, as it is adjustable for fine tuning.
proj. lens
So taking the size of my LCD(15", 381mm), the distance from where the projector will be located to the wall(7', 84", 2,133mm), and the median focal length of the projection lens above(about 223mm), I get a screen size over 140...more than double the diagonal size of what I would like.
When I move things around a bit in the formula to find out what FL I will need on my lens (in order to project a 60" screen), I get about 533mm...the longest focal length I've seen is about 455 on the long throw lens on the same site as the lens linked to above.
So my question is basically...someone double check what I'm doing here and make sure I'm not blowing it. I've searched day and night. I'm pretty sure I'm doing everything right, but obviously I'm not. Placing my projector 43" from the wall for a 60" screen just doesn't seem right.
Thanks in advance for any help.
An externally hosted image should be here but it was not working when we last tested it.
You have the wrong equation. That's your problem.
So with your numbers:
(2133 - 223) x (381) / 223 = 3263mm or 128".
Yes, it's 10 feet diagonal. To get a 60" screen you need to either place the projector closer or get a lens with a longer focal length.
(Throw - 223) x (381) / 223 = 1524; Throw = 1115mm or 43.8".
(2133 - FL) x (381) / FL = 1524; FL = 533mm
60" is not a big screen (in the land of DIY projectors). 100" is very common and 120"+ is not unheard of. Search this site for "opaque projector" and "process lens". I have seen these kinds of lenses with a long enough focal length. Good luck!
An externally hosted image should be here but it was not working when we last tested it.
So with your numbers:
(2133 - 223) x (381) / 223 = 3263mm or 128".
Yes, it's 10 feet diagonal. To get a 60" screen you need to either place the projector closer or get a lens with a longer focal length.
(Throw - 223) x (381) / 223 = 1524; Throw = 1115mm or 43.8".
(2133 - FL) x (381) / FL = 1524; FL = 533mm
60" is not a big screen (in the land of DIY projectors). 100" is very common and 120"+ is not unheard of. Search this site for "opaque projector" and "process lens". I have seen these kinds of lenses with a long enough focal length. Good luck!
ahhhhhhhh...thanks man! haha I had misunderstood the equation. When it says (distance - FL), I thought they meant the distance of the Focal Length, not distance MINUS focal length.
Ok, I have to rework everything now that I'm one clue closer to getting it all worked out.
Thanks again man.
P.S. 60" isn't all that large, I agree. But I'm planning on building two of these things and the first one is just gonna be kind of a test bed that'll go in my bedroom for casual viewing. The space on the wall, and the distance I will be watching it from unfortunately force me to keep the screen size under 60". Any larger and it'll overlap onto windows/furniture/etc., and I'll feel like I'm in the front row of a movie theatre. Still a sizeable step up from watching movies on my 22" monitor or my 13" TV.
Ok, I have to rework everything now that I'm one clue closer to getting it all worked out.
Thanks again man.
P.S. 60" isn't all that large, I agree. But I'm planning on building two of these things and the first one is just gonna be kind of a test bed that'll go in my bedroom for casual viewing. The space on the wall, and the distance I will be watching it from unfortunately force me to keep the screen size under 60". Any larger and it'll overlap onto windows/furniture/etc., and I'll feel like I'm in the front row of a movie theatre. Still a sizeable step up from watching movies on my 22" monitor or my 13" TV.
ha!
ha...I just redid the #s, but I plugged in a 7" screen instead of a 15" and it just happened to come out to a screen that is 59.97".
I guess that solves my problem right there. Perfect.
ha...I just redid the #s, but I plugged in a 7" screen instead of a 15" and it just happened to come out to a screen that is 59.97".
I guess that solves my problem right there. Perfect.
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