Mounting Scroller as Douser

[Amishplumber]

Hi All,

Searched around but couldn't find the answer I need.

I'm projection engineering a show that loads in next weekend and am just getting around to planning things out due to ludicrous overbooking. We have 3 projectors and are planning to douse them using scrollers. I've never used scrollers as dousers before and am drawing a blank on how to actually mount them in front of the projectors. I'm either going to be building custom mounts (i.e. shelves) for the projectors or using some mounts I already have, which consist of a 14" square shelf attached to a rather large yoke I pulled from an old beam projector that are then hung by C-clamp to a pipe. Projectors are all small, garden variety, 2-3k lumen units.

So any thoughts on attaching scrollers in front of projectors, either for my specific situation or in general?

On a somewhat related note the designer has it in her head to "shutter" the projected image for certain moments by taking a frame of dark blue gel and carefully cutting a square hole in the middle. I have my doubts about how well this will work considering how precise and tiny that hole will have to be along with the projected image not being in focus that close to the lens, meaning the edges will not be sharp. Anyone heard of this method before and have experience with it?

Thanks very much!

 

[gafftapegreenia]

You can build a douser out of an old CD-ROM drive, see thread:http://www.controlbooth.com/forums/multimedia-projection-show-control/6801-need-remote-douser.html

Never heard of that gel trick.

 

[Footer]

The scroller thing does work... and yes you have to get a bit creative with the mount. Last time I saw this done the scroller was mounted on the tray that held the projector. A few things to keep in mind with this though... First, you need to make sure frame one is actually clear. Many older scrollers are very worn on frame one creating a kind of frost. Second, use black wrap rolled into the scroll to do the "blackout". I know this sounds weird, but it properly packed it does work. There is also a manufacture that makes a scroll do to just this that gives you a nice "fade" to black as it rolls.

 

[jstandfast]

I'm with Footer on the manufactured dousing scroll. I believe we've gotten them from Wybron on at least one occasion; they may not be in the catalog, but I think they fell off the shelf.

 

[Amishplumber]

Thanks for the replies guys.

I've got a source for a custom dousing scroll, what I really need help with is mounting a scroller in front of a projector.

 

[Footer]

Thanks for the replies guys.

I've got a source for a custom dousing scroll, what I really need help with is mounting a scroller in front of a projector.

If you have an old 6x laying around, you can pop the lenses and mount that to a side arm. The scroller can then hang in that. You can really do a lot of things, it all just depends on where you are hanging it and what is around.

 

[ruinexplorer]

I have mounted them using Unistrut for a frame with a couple of pieces of 1/4" flat iron bolted on it to act as the rails of the lens tube. Obviously you would have to attach the unistrut to your projector mount and safety the scroller.

As for the "shuttering" of the image, you will get a lousy result from the gel being cut. First of all, the gel often has a bit of flutter, so even if you cut the hole perfect for your image, you will not be happy. The best thing to do is to map your image. This uses a program which will cover parts of your image with video black for the areas you do not wish to project. There are a variety of hardware and software options to do this.

 

[metti]

I have aluminum angle channel welded into the shape of a gel frame holder and onto the projector rigging frames I have for my projectors.

 

[howlingwolf487]

The best thing to do is to matte your image. This uses a program which will cover parts of your image with video black for the areas you do not wish to project. There are a variety of hardware and software options to do this.

There, fixed it for you (unless I just don't know what you're talking about…feel free to correct me). I'm not being critical, only correcting the spelling so that it shows up in searches.

Carry on!

 

[ruinexplorer]

Nope, meant it to say map. It is similar to using a matte on framed art, where that is sometimes covering a portion of the image, to frame it. But with projection mapping, generally used on three dimensional objects, you are removing parts of the image so that it will not show on areas that you want projection free.

Here's a video example (though more complex than what is needed by the OP).

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[Robert]

Perhaps take a lens train out of a fixture that the scroller fits, take the lens out, bolt the lens train to a piece of plywood through the focus knob hole and sit the projector on the ply. I think this would be cheap, simple, and quick. Makes it in my book.

 

[joeyfergie]

Reopening this thread. I am looking for the same thing, scroller as a Douser for a projector. The mounting is not a concern to me, but I need to find a gel that can be used to 'Fade to Black'. I can't seem to find any using Google, and unless I am missing something, I don't see any mentioned above. If anyone knows where I can order these, please let me know!!

 

[derekleffew]

I don't know of anyone producing a gradated color media either. If one can deal with steps, one could make a custom scroll that goes
Clear>L298>L209>L210>L211>L299>BlackWrap.
But most have found it better to have the fade to "black" generated on the clip (or via the playback media server), and have the physical douser be the last step, engaged only once the projector is sending "video black," as the "wipe" of the blade is less noticeable that way.

Using an "iris-douser" such as the Wybron Eclipse IT Iris, supposedly allows for a smoother fade, but I have no experience or evidence of this.



I've only used the standard Eclipse Shutter, where the vanes, even in the open position, would likely be objectionable.



See also the thread http://www.controlbooth.com/forums/multimedia-projection-show-control/6801-need-remote-douser.html .

 

[sk8rsdad]

The string I made uses Rosco #26 Primary Red as the shutter material which cuts out most of the light from a projector that has been faded to black. Congo Blue #382 may be a better choice but it depends on the projector. I have also used mylar but found it difficult to get a reliable taped seam. Our current projector has an internal iris and is controllable via ethernet link, so we no longer use the scroller technique.

 

[metti]

First of all, given the video black levels for most projectors, the wipe off going from a clear frame to an opaque frame is noticeable even if the projector is doing its best not to put out any light. Any scroll manufacturer (Apollo, Rosco, Wybron, etc) can make you scrolls with graduations from clear through several NDs and then into an opaque material. I know Wybron in particular has done this in the past for a bunch of people. The other option is to use a custom build gradient scroll. What you will need to do is have a sign shop with a $100,000+ UV Cured inkjet roll printer print opaque pigment gradients on mylar or acetate strips. Then you laminate or adhere a piece of opaque material in a square at the end of the dark side of the gradient. This is a very expensive option compared to a stepped ND scroll but it is the only way to completely avoid the lines during the fade. I know of at least one Broadway designer who always specs this so you might be able to get these sourced through a company like World Stage/Scharf and then you would at least be able to avoid the process of trying the source the printed scrolls yourself.