I'm making an installation school project which need to project an image of 5m x 7m on the floor. But our venue is very small and the height of the room is about 2.4m only! And we only have some very ordinary projectors (no optional lens, not very bright, and not short throw) 🙁
Can anyone please tell me if there's anyway to dramatically enlarge a short distance projection image? ....it doesn't have to be in very nice image quality, but LARGE!
Million thanks!!!!!!
Can anyone please tell me if there's anyway to dramatically enlarge a short distance projection image? ....it doesn't have to be in very nice image quality, but LARGE!
Million thanks!!!!!!
Does anyone have the answer for onio's question?
I am thinking the similar problem. Bascially, i want projected the image onto floor. But the ceiling is only that high...
Plus, can one really mount a projector upside down? would
this cause overheat?
Thank you very much. Any idea will be appreciated.
Jie
I am thinking the similar problem. Bascially, i want projected the image onto floor. But the ceiling is only that high...
Plus, can one really mount a projector upside down? would
this cause overheat?
Thank you very much. Any idea will be appreciated.
Jie
making the image wider
I see two simple solutions, but neither will give you very good quality:
1: Use mirrors to make the projection distance longer. You can make two cheap mirrors out of thin plywood covered with aluminized mylar. Then put the projector on the floor off to the side of the room, pointing straight up. Put the first mirror at the ceiling at a 45 degree angle, so it sends the light to the center of the room. Put the second mirror at the ceiling at a 45 degree angle, so it sends the light down.
2. Put the projector at the ceiling pointing down, but add another lens to shorten the focal length. Try different strength reading glasses lenses until you find one that gives you the right size image. Then you can buy a bigger lens of that strength from a surplus optics place. (Reading glasses are rated by Diopters, and focal length = 1000/Diopters)
I see two simple solutions, but neither will give you very good quality:
1: Use mirrors to make the projection distance longer. You can make two cheap mirrors out of thin plywood covered with aluminized mylar. Then put the projector on the floor off to the side of the room, pointing straight up. Put the first mirror at the ceiling at a 45 degree angle, so it sends the light to the center of the room. Put the second mirror at the ceiling at a 45 degree angle, so it sends the light down.
2. Put the projector at the ceiling pointing down, but add another lens to shorten the focal length. Try different strength reading glasses lenses until you find one that gives you the right size image. Then you can buy a bigger lens of that strength from a surplus optics place. (Reading glasses are rated by Diopters, and focal length = 1000/Diopters)
Thank you, guy.
For the second solution, i have some concern. If you point
the projector vertical down, will that position cause overheat ?
As for the first solution, what kind of specical mirror are out there for this pure reflection purpose? Can i just use a regular home use mirror?
Thanks a lot for the info.
jie
For the second solution, i have some concern. If you point
the projector vertical down, will that position cause overheat ?
As for the first solution, what kind of specical mirror are out there for this pure reflection purpose? Can i just use a regular home use mirror?
Thanks a lot for the info.
jie
big picture
If it was a DIY projector with a MH bulb, some bulbs have a requirement to run in horizontal or vertical orientation +- some number of degrees of tilt. Other bulbs are called "universal position" because they don't care. If your projector has a bulb with a filament (ie. tungsten, halogen) and a strong fan, then it probably doesn't matter how it is pointed. If you are worried, put the projector in it's normal position on the floor. and add a third mirror to send the light up.
There are special glass "front surface mirrors" used to eliminate extra reflections, but they will be WAY out of your price range for any large enough. Reflective mylar is a VERY cheap way to make a lower quality front surface mirror. (You said the quality was not so important.) They will also be very light weight, and so easier to fasten to the ceiling. Measure the cross section of the projector's light path at the point each mirror will be inserted (at a 45 degree angle). These will be big mirrors, and the last one really big.
If you want to see how good (and how bad) mylar mirrors are, buy a square foot at a hobby or craft shop and glue it to something very flat. If the backing is flat enough, it should look pretty good.
On the other hand, you also said your projector was not very bright. You are bound by the inverse square law: Make an image twice as wide, and it will be 1/4 as bright. Try projecting an image as wide as the result you want. That is the very brightest you could get with perfect mirrors or additional lens. Each mirror or lens you insert in the path will take some of that light away.
If it was a DIY projector with a MH bulb, some bulbs have a requirement to run in horizontal or vertical orientation +- some number of degrees of tilt. Other bulbs are called "universal position" because they don't care. If your projector has a bulb with a filament (ie. tungsten, halogen) and a strong fan, then it probably doesn't matter how it is pointed. If you are worried, put the projector in it's normal position on the floor. and add a third mirror to send the light up.
There are special glass "front surface mirrors" used to eliminate extra reflections, but they will be WAY out of your price range for any large enough. Reflective mylar is a VERY cheap way to make a lower quality front surface mirror. (You said the quality was not so important.) They will also be very light weight, and so easier to fasten to the ceiling. Measure the cross section of the projector's light path at the point each mirror will be inserted (at a 45 degree angle). These will be big mirrors, and the last one really big.
If you want to see how good (and how bad) mylar mirrors are, buy a square foot at a hobby or craft shop and glue it to something very flat. If the backing is flat enough, it should look pretty good.
On the other hand, you also said your projector was not very bright. You are bound by the inverse square law: Make an image twice as wide, and it will be 1/4 as bright. Try projecting an image as wide as the result you want. That is the very brightest you could get with perfect mirrors or additional lens. Each mirror or lens you insert in the path will take some of that light away.
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