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DMX Blackout for video projector


Jane

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Make a flappy!!! We had the problem at college, fix a batten of wood above the projector, with black material on, and thread fishing wire/cotton through this, with a lightweight piece of wood on the bottom. Tie off wire, attach to string, run the distance you want and there you go! It's not DMX but its very reliable!

 

I've made a "flappy" as you put it, :unsure:

they sound very primitive but if you've got a low budget they are brilliant only problem is running long distances but I managed about 20m with a couple of boom arms with some PVC to stop it snagging and some black cloth that I nicked from costume lady I think only good for short term though!!

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  • 2 weeks later...
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I have recently bought myself a Wahlberg Projector shutter and I can honestly say that it's one of the most satisfying pieces of kit I have purchased for a while.

I'm sure most people who have ever had to combine video projection with entertainment lighting at any point have been frustrated by the the light output from video projectors even when displaying a 'black screen'. It can ruin lighting states and light your stage crew wonderfully during blackouts.

In past years I have tried a few methods to avoid this, including the old piece of cardboard, gaffa tape and string method, even the advanced cannbilised cd player drawer and long remote wire option. But no more, for the rather princely sum of about £160 before VAT I forked out for a wahlberg shutter. It's a simple enough piece of kit, a DMX controllable motor in a compact sturdy box which has a black plastic 'flag' on the front (you even get a choice of two sized 'flags'). Quite simply you set it up so that when the DMX channel is at 0 the flag is down in front of the projector lense and thus obscuring all light output, then when you fade the channel up the flag raises and output is restored onto the screen. Simple and effective. I'm probably over excited, but it's an issue which has always put me off including projections in my theatre work which has finally been resolved. Being DMX obviously it can be plotted into a cue stack like any other fixture so one less thing to think about.

Anyway, I've had my say.

 

 

btw, I bought mine from a company called Stage Sound Services, a quick google will turn up their website or contact details I'm sure.

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I've only used the shutter on quite limited DMX rigs so far where it occupied the highest address in the rig. It was on DMX channel 100 with a dozen scrollers at 80-92. Can't say I noticed any jittering of either the shutter or the scrollers but I'll look out for it next time I use it in conjunction with some movers.

 

p.s thanks mods, I had just posted this when I saw this existing thread and slapped my forehead :)

 

p.p.s They also make a version which has an in-line on/off switch so it can be operated manually without the need for a DMX controller or lighting desk, although it adds a little to the price which is a bit high for what it is. However, as you can see by this string there are not many places to get products like this so you can't blame the retailers for 'naming their price' so to speak.

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I've just had an interesting conversation with a collegue and thought you lot might like to know the outcome.

 

For the new production of Lord Of The Rings, a device has been made for all the video relay units that is DMX controlled. Every time you program in a blackout on your lighting desk, you add the channel of this device and it fades the pictures to black.

 

Not too sure on many more details, but it sounds quite cool. So, when the director wants a blackout, he actually gets it, rather than having light spill from the monitors on the front balcony / orchestra pit etc.

 

 

Can anyone give anymore details on these things?

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Just wanted to mention Brian Friel's The Faith Healer (USA cast Cherry Jones, Ralph Fiennes and Ian McDiarmid - I don't know the Dublin cast) on Broadway had a remarkable video black effect:

 

Between scenes, a full stage traveller came across the proscenium and completedly back-packed on the opposite side of the proscenium. As the light-colored soft goods appeared (with zero fullness), a video of a windy heath completely filled the fabric at all times, with no overscan ahead or behind the constantly moving soft goods. The furniture was shifted as the curtain moved, so that no stagehands were seen, and the next scene was revealed ready for use.

 

I suspect this wasn't as hard as blacking out a speaker-support super-bright projector run from PowerPoint. The picture was never intended to be dazzlingly bright in The Faith Healer. But the stage was quite dark, so any extra image would have been conspicuous.

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What's worked well for me in the past (and seems to work for those venues I've

introduced to it!) is using an old computer CD drive.

 

If you strip the drive down, removing all of the components (head, etc) except for the

drive tray and motor, and then connect a 5V DC power supply to the motor via

a polarity reversing switch...

 

Used this for our production of Wild Party and it worked brilliantly routed it through our spare microphone tie lines. Not DMX but our AV Op didn't care.

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For the new production of Lord Of The Rings, a device has been made for all the video relay units that is DMX controlled. Every time you program in a blackout on your lighting desk, you add the channel of this device and it fades the pictures to black.

 

Can anyone give anymore details on these things?

 

They probably used a device like this (scroll down to 'DMX Switch Driver Board'). Although this unit has 4 inputs, you would only need one. To blackout just switch it to another unused channel to cut the video signal to the monitors.

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  • 4 weeks later...

Finally, as my name was mentioned back in April I have got around to some photos!

 

Front View

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007014.jpg

 

Back View showing DMX & Power

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007011.jpg

 

Side View showing obligatory safety point

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007010.jpg

 

On a projector in 'Open' position

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007016.jpg

 

On a projector in 'Closed' position

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007015.jpg

 

These are the two shutter mounting position arms which have been used on 5 projectors so far, yes they are made with black wrap, cardboard, and gaffire, but they were only to test the sizing!

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007021.jpg

 

Total cost around £50

 

Companion project, DMX mouse left click for those powerpoint presentations !

http://i148.photobucket.com/albums/s23/preeves_album/BR/th_13052007019.jpg

 

Regards,

Paul

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