Laser alignment for projector/screen set up? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 13 Old 03-22-2005, 01:25 PM - Thread Starter
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Curious if anyone has used a laser level or other laser alignment device to set up a screen and projector. In most theaters, the screen positioning is less flexible than the projetor positioning, i.e. the screen must centered on the front wall. I would like to be able to mount the screen in place and then attach a laser to it somehow that will shoot out a solid line on the ceiling perpendicular to the center of the screen. Then I can just measure from the screen to the correct distance on the line, measure left or right a few inches to account for lens/mount offset, and then mount the projector. Voila, perfectly squared image on the screen.

Anyone know of a laser device that will do this?
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post #2 of 13 Old 03-22-2005, 01:58 PM
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I used one to essentially accomplish what you describe.

It was not quite as straight forward as you envision. Most "home grade" units are not designed to allow accurate angle measurements. A survey quality instrument should allow you to easily do it as you describe.

I used my home unit to establish a line parallel to a known perpendicular wall to the screen wall. Placing marks on the screen wall and the ceiling at the projector position gave me reference points for alignment of the screen and projector. I also used the horizontal line to align the projector with the top of the screen.

Good luck with the project!

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post #3 of 13 Old 03-22-2005, 02:08 PM - Thread Starter
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Thanks for the reply maddogmc. Having to use the wall as a reference is something I'm trying to avoid. In most cases the walls are not truly perpendicular to each other due to variations during construction. That's why I would prefer to have a device that I can attach directly to the screen.
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post #4 of 13 Old 03-22-2005, 06:25 PM
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Oh.. sorry, I didn't consider your walls being that bad. Mine are fine but everyone has their own idea of what an acceptable deviation is.

I will admit that, in the past, I have used a micrometer to measure the thickness of wood. Hopefully, I've become a little less anal as I've gotten older!:D :D :D

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post #5 of 13 Old 03-22-2005, 09:39 PM
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Well, an easy way would be to get a laser pointer in the center of the screen and use something like a speed square to make it perpendicular to the screen. That should show you where your projector should be (+/- a few inches). Drop a string (with a weight) from the ceiling and the right projection distance and if the laser hits the string, then that's your spot.

There are no stupid questions, but there are a LOT of inquisitive idiots. Me being one of them at times.

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post #6 of 13 Old 03-23-2005, 06:34 AM
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I've got 20 bucks for the first manufacturer that builds level and line controls into their projectors. Would make life so much easier if they would.
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post #7 of 13 Old 03-23-2005, 07:01 AM
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I'm sure that $20 is enough incentive to get them to drop all the other advancements and focus on level and line controls. You couldn't have at least offered a beaner.




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post #8 of 13 Old 03-23-2005, 07:44 AM
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Quote:
Originally posted by Stew4msu
I'm sure that $20 is enough incentive to get them to drop all the other advancements and focus on level and line controls. You couldn't have at least offered a beaner.

Stew

Allllllll right..... $25.... but not a penny more! ;)
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post #9 of 13 Old 03-23-2005, 04:23 PM
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Not to discourage your high-tech idea (I have a rotary laser that will plot perpendicular lines, and that's the route I would likely go), but there is a low-tech answer.

Plumb a line up from the left corner of your screen to the ceiling, do the same from the right corner.

Measure the same distance from both marks on the ceiling (eg 15') and draw arcs. Where the arcs intersect are perpedicular to, and in the center of, your screen. You might need a little math (or trial and error) to get the throw you want.

Tim
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post #10 of 13 Old 03-23-2005, 06:24 PM
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just take the projector .... hold it in your hands, turn it on.. and stand where it puts a good image on the screen.. then mount it there and enjoy a good flick..
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post #11 of 13 Old 03-24-2005, 08:11 AM - Thread Starter
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Mr. Tim, in lieu of finding a good device, your geometrical method is the route I'll have to go. Thanks. BTW, what model of rotary laser do you have?

Suprfly, if I were only mounting one projector, and it were mine, then your method might be good (still tough to get a perfectly square image quickly using trial and error). I'm installing lots of projectors that I don't own, so I don't like the idea of dropping someone else's $4k projector and smashing it while I'm trying to square up the picture.
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post #12 of 13 Old 03-24-2005, 09:12 AM
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Expanding on Mr. Tim's post...

If you are going to be mounting a number of projectors, I would suggest that you make a "tool" for doing this easily. Take two 30 lb. picture hangers, 50' of thin steel cable, a small piece of tape, and a pencil. After mounting the screen you:

1. Calculate the throw distance for a specific projector

2. Calculate the distance from the projector lens to the screen corners

3. Locate your ceiling points above the screen corners

4. Push in the picture hanger pins at these locations

5. Measure your wire for the total distance from the projector lens position to the two picture hooks

6. Attach a small piece of tape to the center point of the wire

7. Attach the wire ends to the picture hooks

8. Stretch the wire from the screen corners to the projector location, using the taped center marker to precisely locate the projector lenses position.

I guess you will also need a small calculator capable of doing SqRt unless you relish doing those long hand!

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post #13 of 13 Old 03-24-2005, 02:03 PM
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Quote:
Originally posted by Jonathan DA
Mr. Tim, in lieu of finding a good device, your geometrical method is the route I'll have to go. Thanks. BTW, what model of rotary laser do you have?

Suprfly, if I were only mounting one projector, and it were mine, then your method might be good (still tough to get a perfectly square image quickly using trial and error). I'm installing lots of projectors that I don't own, so I don't like the idea of dropping someone else's $4k projector and smashing it while I'm trying to square up the picture.
I have a Lasermark rotary.. I think it's LM3. It projects a continuous beam out of the top and then of course there's the rotary beam on the hoizontal plane (90D to the top projecting beam).. Lay it on it's side and you project right angles for what we're discussing.

I have seen less expensive models that aren't rotary.. They project 90D angles. The beam isn't as strong, but it wouldn't need to be for this application. I believe it was called "PL3"

Tim
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