Double bladed DMX Shutter

[Gareth A]

I am just wondering whether anyone has ever seen a double bladed projector shutter - that works like a clock hands mechanism - so you have two different blades overlapping each other on 2 DMX channels. . . ? Pointless I know for most applications, but we are trying to do an application where it needs to have a 3d filter drop in and out so it can go between full 3d and full brightness 2d and also then have a blackout shutter as well. A scroller was thought of with clear gel, black wrap and the 3d filter in it, but its not possible due to the nature of the installation.

 

Any thoughts?

[DrummerJonny]

Could you possibly just use 2 Shutters?

[Gareth A]

Could you possibly just use 2 Shutters?

 

Now I did think of that actually and replacing the other shutter for the filter - also thought of using a shutter with the 3D filter and then using the projector internal shutter, but its never as smooth as the paddle crossing over gently.

 

The reason why I discounted the idea of 2 shutters - is we have 2 projectors for the 3d, and both need to do the 2d and the 3d seperately from each other - thus would require 4 shutters - and the chances of the paddles bending slightly with the heat, angles over a long panto run seem to cause a little concern.

 

So in short - probably not a good idea. . . . .

 

Thats also the reason why the scroller went out - because making 2 and getting them to fit exactly at close range may not happen. . .

[Jivemaster]

Shutter like this (from plasashow) http://www.srslight.com/index.php?index=pr...&product=21 and replace the solid paddle with a sector filter Open/Black-Out/3D

[TomHoward]

We've got a Milford Instruments servo control board and a servo with a bit of matt black stiff card stuck on it - never had any heat issues. Milford do an 8-way servo board (1-568), pair that with four servos (about a fiver each), two opaque shutters and two filters, and you could do the whole lot with change from £100.

 

Assuming the 3D filters are polarising you'll have to be careful with the angles, as obviously they'll rotate into place so need to get the final positions right, compared to on a scroller.

 

You could almost do it on one shutter with a servo board - ours turns through 180 degrees, so 60 degrees of open, 60 of opaque and 60 of filter should allow you to set it halfway for filter and all the way for blackout.

[ImagineerTom]

Why would you need 2 scrollers - you could get it all on one scroller and then you'd be using very tried and tested technology?

[IRW]

Why would you need 2 scrollers - you could get it all on one scroller and then you'd be using very tried and tested technology?

 

The OP is using two projectors.

 

I second the idea of using one shutter with a 'double' sized paddle on it. We have a Wahlberg DMX shutter which, as with TomHowards, rotates through about 180 degrees.

 

See the bottom of this page for a handy visual example of the shutter!

 

Ian

[Gareth A]

Why would you need 2 scrollers - you could get it all on one scroller and then you'd be using very tried and tested technology?

 

I also did think of using string and cardboard as thats very tried and tested too ;)

 

At some points only 1 projector will be in use - sometimes 2.

 

In 3d - both will be in use. In 2d - its dependant on which file is running - so sometimes will be projecting either from 1 or both projectors.

 

But yes - a scroller is tried and tested - and definately works best. Ill agree, but in this application it just wont.

[ImagineerTom]

I still can't see why you can't use a scroller.

 

I've worked with 3D (a couple of major theme park installations and several full production shows) so have a better than average grasp of it.

 

Since I assume you're using polarized 3D then I can think of several very good reasons why a traditional "rotating" shutter won't actually work (and even if you get the alignment right the smallest defect or vibration would throw it out completely ruining the effect for the ENTIRE audiance) - some sort of "gate" style shutter system might work but then you'd have secondary efficiency issues if you don't have the films reasonably perpendicular to the projector.

 

2 scrollers (set as film - blackout - open) configured for left and right will be a tried and tested technology that will actually be dependable and won't be forever jumping slightly out of line. "space" shouldn't be an issue as the ACTUAL positioning of your projectors doesn't matter too much as they can be keystoned / corrected to compensate. If you're using 2 smaller projectors (office size) then you could get away with one scroller from a flood / battern and a bit of creative programming/splits

[kitlane]

When I were a lad we used some old colourwheels with black wrap in all but one of the holes. I would think a 3D filter in one of them would be pretty stable.

[ImagineerTom]

No it wouldn't (unless the op is using one of the proprietary circular polorisation systems - in which case he wouldn't be asking this question as you can't DIY that technology) as it is absolutely imperative that the left and right filters are aligned perfectly at 90 degrees to eachother and in a matching alignment to whatever configuration specs they're using. If either filter is so much as 1degree out the entire 3D effect will fail, if both filters are not aligned the same as the specs then the entire audiance will have to tilt their heads over at an odd angle to make it work. If you're planning on moving the 3D filters then you need to ensure that they can be moved without changing their alignment otherwise the system won't work.

[timtheenchanteruk]

seems like a job for the old semphores

 

http://www.strandarchive.co.uk/control/eff.../semaphore.html

[landy]

I second the idea of using one shutter with a 'double' sized paddle on it. We have a Wahlberg DMX shutter which, as with TomHowards, rotates through about 180 degrees.

 

See the bottom of this page for a handy visual example of the shutter!

 

Ian

 

You are able to get metal paddles for the Wahlberg units, we have had some out for over a year(s) on shows with out distortion.

[kitlane]

No it wouldn't (unless the op is using one of the proprietary circular polorisation systems - in which case he wouldn't be asking this question as you can't DIY that technology) as it is absolutely imperative that the left and right filters are aligned perfectly at 90 degrees to eachother and in a matching alignment to whatever configuration specs they're using. If either filter is so much as 1degree out the entire 3D effect will fail, if both filters are not aligned the same as the specs then the entire audiance will have to tilt their heads over at an odd angle to make it work. If you're planning on moving the 3D filters then you need to ensure that they can be moved without changing their alignment otherwise the system won't work.

 

In that case I don't think any reasonably priced DIY system based on re-purposing equipment is going to work.l

[TomHoward]

Servos do resolve the position and update it though, so if they were moved after positioning they would return to that place. A scroller would be more stable for the X-Y alignment though. In my experience I've always found some shadowing with polarising 3D specs anyway, it isn't exactly the most stable of effects.