Wide angle beamer or rig?

Apr 23, 2012 at 7:47pm

Wide angle beamer or rig?

Hi There i have to project images on the stage, the quality is not so cruicial but i need to cover at least 10 x 4 meters with one projector. I’m not such an expert but i fear for something like that i need a high ceiling with a normal projector. 1st question: what is the angle of coverage of an average projector (to calculate the necessary height)? 2nd: Is there a riggable mirror to back project the image in a wider angle? (i think i saw something like that but i cannot recall the model/brand)
Cheers
Alberto

#57982
Apr 23, 2012 at 9:05pm
#208062
Apr 23, 2012 at 9:28pm

Hey Alberto, Dieter here.

I’m using 3 of these wide-angle beamers: http://www.benq.us/product/projector/ms612st (cheapest wide-angle/short-throw I could get at the time).
10m width would mean about 10m projection distance with these.
What’s against using multiple?

grtz D.

#208063
Apr 23, 2012 at 10:08pm

Hi,
the calculation is: imagewidth X f = projection-distance (f is the opticfactor)
Best

#208064
Apr 23, 2012 at 11:14pm

10x4m with one projector? Sounds like you’d have a bad time doing this.

#208065
Apr 24, 2012 at 2:19am

This is the patch I use for projection size:

– Pasted Max Patch, click to expand. –

I also own the Benq MS612st. It is great, but somewhat less bright than a Sharp I have with the same lumen rating. I’m not sure why.

If you wanted to use that projector on your projection, it would have to be 9 meters off the ground.

As always, the brightness you can have if you need to project 10 meters wide will depend on the surface, the ambient light and the power of the projector. There are alot of projectors available nowadays, so it is just a question of how much you want to spend.

You could use a convex mirror to change the projection and cut down the distance, but then you are opening a whole host of other considerations about distortion, focus and brightness.

#208066
Apr 24, 2012 at 8:50am

> You could use a convex mirror to change the projection and cut down the distance, but then you are opening a whole host of other considerations about distortion, focus and brightness.

If anyone knows feasible methods for doing this, I’d love to hear about them!

#208067
Apr 24, 2012 at 10:41am

Hi
I use the following workaround:

1. definition of imagesize
(your 10X4m need to be precised, either 4X3 or 16X9, meaning in AR 4/3 your image is in size max. 5,33 m X 4m, in AR 16/9 in size max. 7,1m X 4m)

2. definition of the possible position of the projector (depending of room size, preference for ceiling mount) (In your case, ceiling mount means height 4 m in reverse mode)

3. choice of projector (depending of image quality to be achieved, budget, imposed disponibility of the venue par ex.)

4. defining of possible compromises (depending of point 1 to 3, the surface on wich will be projected, the ambient light)
additional possibilities: preparing the video with boosted colorintensity (carefully !) in order to counterbalance, ambient light zero, painting the wall on wich will be projected (if possible, is very usefull !!) etc.)

Best

#208068
Apr 24, 2012 at 4:14pm

@dtr:
The University of Singapore’s Augmented Reality lab used to have some open-source C++ resources which addressed some of these issues, and the math was easily extractable (if you can follow the code). That was years ago, so I have no idea if that stuff is still available.

#208069
Apr 25, 2012 at 9:25am

Thanks, will check that out. I’d love to find a way to project in space (light rays in smoke/fog) without having all the rays visually originating from the beamers lenses. So I could have parallel rays, for example.

#208070
Apr 26, 2012 at 9:02pm

Hi all thanks for the answers. I try to have mobile performance so that i don’t have to necessarily move around with a beamer, i was thinking of having just a manufactured rigged mirror to expand the projected image in the back of the projector. Maybe it’s science fiction, maybe not. I would need a curved mirror. In principle i don’t have personal problems with distortion in my case, luminosity loss or whatever aberration and the show i in total darkness so also that helps. The ceiling might be higher depends on the theater but i’d like to be ready for extreme cases. Anyway nobody knows of somebody creating these kinds of external mirrors/lenses?
Would solve many problems and transform any beamer into short throw..
Alberto

#208071
Apr 26, 2012 at 9:29pm
#208072

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