Steep projection angle

Hi guys,

Could the following setup be done without the too much loss of brightness and resolution on the lowest parts of the screen? Any suggestions are welcome.

For the moment, front or retro projection are out of the question.

Thanks!

Peter,

you're pushing physics a bit too much.
Regarding brightness there will be a significaqnt difference between top and bottom, but the bigger problem will be your lens focus.
It is impossible within that distance to get an equal focus on your screen.
Whatever you will do I would expect minimally 60% of your screen will be out of focus, which is not that good for video content. :-)

Best

Rolf

Rolf,

Which minimal distance do you suggest? I can go higher.

Will it help if i also use 2 projectors and create a greater distance? Teh jpeg is still with the 640 but you can discard that.

Peter

Peter

I would see if you can get a test setup together - with projector(s) and screen.

It may work on paper but not look good in reality.

I think this is impossible to say what will or won't work without actually trying it.

regards

Nev.

Peter

Further to my email this morning - this can't be done with your current setup.

2 projectors, as you suggested, is just complicating an already difficult setup - Think simple!

A mirror positioned in the correct position might be your best solution. Golden rule to remember when working with mirrors is 'angle on = angle off' but you cant do this with 1 projector.

Even if using a mirror - with the dimensions on your drawings, there would be no space to rig the projector to get enough distance to cover the whole screen - and you would still encounter some of the same focusing issues as previously discussed.

The screen dimensions of 10m x 6m is impossible to cover with any single projector at a distance of 3m - there is no lens that exists that could cover the whole area.

Check out the barco lens tool to try and work out your minimum distance! Using a 0.8:1 lens on your 10x6m screen, the projector has to be 12m away - and thats straight on. http://www.barco.com/presentation/en...calculator.asp

You may be able to cover the screen with 2 x projectors at about 6m - but you would still need to overlap and blend them. - This still doesn't take in to account your steep angle, focus and brightness between top and bottom.

I suggest that you try and look at getting a greater distance between the projector and screen, preferably with a less steep angle

Alternatively - use an LED screen!

Simon

I knew this would be difficult if not impossible. I already proposed leds but i'm afraid the budget wont allow it. I will try to gain more distance between the projector and screen.

Thanks guys!

Been thinking again about the led solution. It needs to look like a good projection and be relatively affordable. This week i saw the barco Ilite 6 XP and was quit impressed but i suppose this will be too expensive. Any suggestions on that (it's a touring production with little setup time)?

Stealth from Element Labs,

pixel resolution is only 25mm but its easy to rig and tour

Ian H

Hey Peter,

About 6 months ago I created a design proposal to do something you are trying. The installation was for a clients penthouse. The throw distance was about 6' and the screen size was to be 18' tall.

I haver attached a pic showing how we were going to use stacked projectors and bounce mirrors to do this. The mirrors were huge. The blending was not going to work because of the steep angle difference between projectors.

If you look at the pic, you'll see that one projector was below the screen and the other was above. The good news was that we were able to use 1.8 lenses. With 0.8 lenses and better mirrors, it might be possible but nuts.

Quote:

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Originally Posted by SourceChild

I haver attached a pic showing how we were going to use stacked projectors and bounce mirrors to do this. The mirrors were huge. The blending was not going to work because of the steep angle difference between projectors.

If you look at the pic, you'll see that one projector was below the screen and the other was above. The good news was that we were able to use 1.8 lenses. With 0.8 lenses and better mirrors, it might be possible but nuts.

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We will try to do something like this (also thanks to fons from improve) using a fixed lens 1.2, so there will be only 1 mirror. What do you think? And what the blending in this situation? There will be 3 projectors and 3 foils to cover the backdrop.

Oops, forgot the picture...

Hi guys,

Meanwhile we 've worked on a retro setup. But what do you think about this angle in front? It's a lots less steeper.

Thanks.

Peter,

I think this might work, nevertheless the calculation of your projection axis should be done with the center beam, not outer beam.
The most important thing in your new Setup is the much smaller Screen and that you can use longer optics than before.

Every Video Guy still would kill you for that, but I would say it will work, did a couple of these angles with Dl2s, 3s and similar

Best

Rolf
www.chaoscenter.net

Quote:

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Originally Posted by rolfwenzel

The most important thing in your new Setup is the much smaller Screen and that you can use longer optics than before.
www.chaoscenter.net

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Rolf,

What exactly do you mean by longer optics? 1.2 or 0.8 lens?

I've included a new steeper design. What do you think about that?

Thanks,

Peter

Oepsi, the angle isnt to the center of the screen, didnt sleep enough...

Peter,

with 0.8 Optics this Setup would never work, as 0.8 needs to be "mostly" on axis.

With 1.2 and beyond the game looks easier as you got much more depth in your focus.

Regarding Distance this looks to me like a classic Zoom Lens like 1.5 - 2.5 or similar. And that's what I have done before with DL2s in this angle, which worked.

In a few months I am hopeful to be releasing a lens that will do asymmetrical parabolic distortion. Basically extreme reverse keystoning. The lens theoretically should allow for angles of close to 70 degrees off axis. I am speculating only a 15% light loss.