# What Projector for Rear-pro full width onto Cyc?



## gwpac (Dec 17, 2009)

Hi guys, just been reading through a few other threads kind of similar to this, but with important differences...

We currently have a NEC MT1075 projector (1024x768, 4200 ANSI lumens) which actually does a reasonably nice job of rear projecting onto our cyc.

However, we are starting to look at one that will do full width projection (the NEC only does about 12metres/500 inches diagonal, or a width of about 300 inches), which for our cyc would be about 16 metres wide (about 630 inches) and 6-7 metres high (about 250 inches).

The projector position would be about 5 metres (16.5 feet) behind, and just above the top level of the cyc.

Obviously the brighter the better, but understand that it's not going to be as good as a dedicated rear-pro screen.

More than half the time it will be used on a real rear-pro screen (but much smaller than the cyc), but it would be great if it could remember a few set sizes and focus depths so we could easily switch between screen and cyc settings.

Anybody done anything similar and have recommendations on models? prices?

Thanks!


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## Footer (Dec 17, 2009)

Your going to need a very, very, beefy projector. Odds are you will have to swap out lenses in order to get your two sizes. When you are projecting onto this cyc, are you using the stage for performance or are you using it as a glorified movie screen? 

Eiki is one of my favorite projector lines if you are within a budget. Of course if you can go Barco or Christy, do. 

Also, are you interested in playing back HD content at full res? 

Their Theatre and Powerhouse projectors are very bright and have a good feature set. They weigh in at 10k-15k lumens. You can pretty much double the lumen count to get the price you will pay. Keep in mind also lenses cost a good amount of cash as well.


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## museav (Dec 17, 2009)

630"x250" is a 2.52:1 ratio while a widescreen projector is going to create a 16:9 or 16:10 ratio image. If you tried to use a single projector to fill the width you would actually need to project a larger image vertically, say more like 354" to 394" high and then only use part of that vertical image area for your actual content. Or you could fill the 250" height and have a 400" (33.33' or 10.1m) to 444" (37' or 11.3m) wide image.

You noted having 5m or about 16.5' feet behind the cyc. Assuming that distance would include the projector depth and any ventilation and cabling clearances, that's probably more like maybe a 15' or or 4.5M throw distance. With a fixed, very short throw lens that probably relates to around a 18' to 21' (5.6m to 6.4m) wide image, a bit short of the 52.5' or 16m width desired and also not filling the cyc height. Adding to that, the lenses required to get such short throw distances typically require the projector to be on the centerline of the image both horizontally and vertically, so that would not seem compatible with a projector position above the top of the cyc.

What are you currently doing? The 500" diagonal, 4:3 format image you noted for the MT1075 represents a 400" wide by 300" high image (see, that 3:4:5 right triangle stuff can come in handy), which would seem to already be exceeding the cyc height noted. In addition, to create a 500" diagonal image for the MT1075 also requires a 614.8" throw distance, which with the depth of the projector means needing over 52' or almost 16m of space to accommodate the throw and projector. Because of these issues, one seems to be able to safely assume that you are actually creating a much smaller image than 500" diagonal. Since the brightness required from the projector in order to maintain the same image brightness goes up based on the image area, it would be necessary to know how large an image you are actually projecting now in order to assess what might provide a comparable result for a larger image area.


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## gwpac (Dec 17, 2009)

Museav: Aha! You're absolutely right. In my effort to be as precise as possible, I was looking at the maximum projected size in the manual for the NEC, which of course would be at a much larger distance than from where we usually project. In actuality the largest size we are getting from that distance is more like 4x3m (13ft x 9.8ft) - Roughly.

Regarding either cutting off image vertically, or fitting vertically, but not going full width. Mmmm, it's something that we'd have to weigh the pros and cons of, but those measurements are probably something we could live with. Actually, you know what? The upstage area (where the projector is) is actually narrower than the rest of the stage area - we have fixed choir risers behind the cyc bar. So projected light probably can't actually go much wider than 12m anyway before getting cut off by the side walls of the choir area. So your suggestion of filling the 250" height of the cyc and only going to roughly 11m (440") width might be pretty close to the mark anyway.

The distance to projector is fairly close to the 5m (16.5ft) I mentioned. Ideally this would be from the top line of the cyc as I mentioned (where our cyc lights are situated). However we also have a hatch at the back of stage at pretty much mid-cyc height, so if necessary to project from centre horizontally as well as vertically, we could probably do that too. We are blessed (and cursed) with a very flexible venue! From those specs, what kind of lumens do you expect would give a comparable image to what we are using now?

Footer: The stage is used for performance, presentation etc. So for the most part cyc projection is in addition to something else going on on stage in front of it. I will look into the brands you mentioned. Funny and useful calculation you suggested for expected budget (lumen x2 = $$)


Thank you both for your wise words!


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## ruinexplorer (Dec 17, 2009)

I only know of one manufacturer that has lens memory for multiple positions and that is Digital Projection. Cirque uses them on LOVE, the Highlight series I think (if they even still make that model). Many people are losing confidence in Digital Projection due to their service structure for relamping. However, these projectors are most likely out of your budget. There are some other projectors that will store files to digitally adjust an image so that you can switch files per viewing surface, but you can only focus on one point. 
Features that I would recommend are lens shift (horizontal and vertical) and either wired remote or ethernet connectivity (so you don't have to try and adjust the projector with line of site remote). These will give you better flexibility without having to move your projector.


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## gwpac (Dec 17, 2009)

Thanks ruinexplorer.

The set memory for different screen positions isn't really a deal breaker, because it will never happen within a show (although now that I've said that, you can bet someone will ask for it!). But often people will want to use our smaller rear pro screen at the front of stage, rather than full cyc width at the back. We are used to moving and refocussing for different shows, so that's not a huge deal. Would just be nice.


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## museav (Dec 17, 2009)

A number of projectors offer lens preset capability, I've used them for 4:3 projectors that fill a widescreen format screen height for 4:3 images and then zoom out to overscan top and bottom for widescreen images. However, the very short throw lenses (0.65-0.8:1) that might be required are typically fixed focal length. To get any zoom capability you might have to go with a longer throw lens or change lenses, thus supporting both a large image and a smaller image may require getting two lenses and changing them for the different applications.

If you wanted a 250" high by 400" to 440" wide image then even with a very short throw lens you might need around 270" to 350", about 22.5' to 29.2', of throw. Add to that the depth of the projector and some clearance for ventilation and/or cabling and you are probably close to needing 25' to 32' (7.6m to 9.75m) of clear depth to the screen for the projector and throw. If you do not have that much depth you could look at mirror systems, although they are probably impractical in such an application. Otherwise you start looking at multiple projectors or a smaller image.

If you currently have 13'x9.8' and a 4200 lumen projector and were to go to a 250" x 400" to 440" image, the latter would require roughly 23,000 to 25,000 lumens to achieve the same brightness on the screen. The lens and other factors could affect the actual value, but that puts you in a much different class of projector.


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## SHARYNF (Dec 18, 2009)

just to expand a bit on what Brad is talking about you are probably looking at a Christie roadie HD30k (the 25k is obsolete) this without the lens is list of 165 grand typically sells for around 125 grand, lamps are 3 thousand dollars a piece and the unit weighs about 320 pounds. A mirror MIGHT be possible you would have to look at the size of the image at about 10 - 16 feet, and have a mirror of that size so that you could fold the distance so you would mount the projector 10-16 feet back from the mirror at an angle of projector and mirror and have the mirror 10-16 feet back from the Cyc. It would definitely be a very expensive deal

Sharyn


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## gwpac (Dec 18, 2009)

OK...wow. That's way more than I thought we needed. Not having done the maths, I was thinking, well if we have a 4200 lumen doing an ok job, if we bumped it up a couple of thousand to 7-8k we'd be rockin. But you guys have certainly put as straight there.

We may have to look at front projection from the balcony edge or dropped from a catwalk to get around the ultra short throw issue, and I guess that also means a small savings in lumens because it's not going through the cyc. But that size may still be out of our league. I think it's probably time to get some reps in to demonstrate!

Thanks so much for all your wonderful calculations and help everyone!

Cheers.


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## museav (Dec 18, 2009)

If you double the size of an image, that is double the height and width, then it is easy to think that twice as big means twice the area when since both dimensions are doubled the area increases by a factor of four.


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