# Multiple Projectors v. One Projector



## Sean22 (Jan 20, 2016)

Thoughts on using multiple projectors to achieve a certain level of lumens, versus one projector?

Projector A - 
7k, lower contrast ration
Projector B -
12k+, higher contract ratio

If I we're to overlay multiples of the 7k, would I actually achieve an equal or great lumen brightness? Would the contrast ration decrease even more??


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## Fountain Of Euph (Jan 20, 2016)

I would think that it would become brighter, since the lamps are doubled, however the challenge would lie in getting the two in focus. 

Sent from Taptalk for Android, this was.


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## Sean22 (Jan 20, 2016)

Fountain Of Euph said:


> I would think that it would become brighter, since the lamps are doubled, however the challenge would lie in getting the two in focus.
> 
> Sent from Taptalk for Android, this was.



The multiples would stack and keystone to match.


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## ruinexplorer (Jan 20, 2016)

It actually doesn't double. This is a common misconception.


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## seanandkate (Jan 20, 2016)

I think the physics of it says it would be a bit brighter, but I would test this to see if you have latency issues between the two projectors and the source. Even if they line up perfectly, you probably won't be happy if they aren't hitting the same frames at the same time. And note that by using both, the nice swishy 12K projo will take on the contrast ratio of the crappier of the two projectors, at least on the dark end of things. Would be an interesting test though.


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## Morte615 (Jan 20, 2016)

There is a brightness gain by doubling up projectors, though as stated above it's not double, actually I think it's like 1/4 or something. But really it depends on the needs of the show/venue. If it is a one off or short run and is not show critical (or budget is tight) I would just get the brighter projector.
But say you have something where if you end up with no projection it's a show down situation then I would consider 2 projectors. That way if a lamp dies or something mid show you at least still have something on screen, though dimmer. And that goes with if it is a long running show and/or you have budget to burn. Also I could see using multiple projectors when the cost ratio ends up cheaper to purchase/rent multiple projectors to hit the same luman. 
So yes it's possible but I rarely see it.


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## Sean22 (Jan 20, 2016)

The run is over a month so the rental is expensive, but i have access to three 7k projectors that are the same model. would just just have to rent lenses.
So, would be seeing more like a 10.5k? RP is black with s scrim downstage of it, so I feel like I should be able to get decent blacks and the added punch should help compensate ... getting both options to test isn't really an option due to scheduling of the space.


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## ruinexplorer (Jan 20, 2016)

Things to consider. I agree that having two projectors stacked is great for critical images in case one inadvertently loses signal/lamp. Having two projectors will also gain you the ability to have more options with future productions (two screens, edge-blending, etc.). However, maintaining a single projector will be easier and likely more cost effective.

The actual "brightness" that you will get by stacking two projectors has a number of variables. At full white, you will get close to the combined intensity of both projectors, but in reality, you won't be just projecting full white. Depending on the technology used to create the image (LCD, 1-chip DLP, 3-chip DLP, etc.) the perceived brightness will vary greatly. A 3-panel (LCD) or 3-chip (DLP) projector will have a brighter color spectrum than a 1-chip (DLP) projector with the same lumens. This is because the projectors are measured for their brightness at a full white field. This means all light is being projected out. As soon as you color an image, you no longer are putting out the same amount of light as it is blocking the light from some of the colors. Depending on the color wheel in a 1-chip projector, you could have 1/4 the output of the 3-chip projector of the same lumens.

Now, since you are doing RP, will you be able to project the image with at least a standard lens? As soon as you try stacking an image with short-throw lenses, you will likely run into some extreme challenges.


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## irked (Jan 20, 2016)

Also be aware that as you add projectors, your video black gets brighter and brighter. I don't know if it'll be an issue in your situation, but I typically end up running remote shutter control to all my projectors so that we can get an actual black blackout onstage.


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