Digital Projector Shutter

[lxkev]

Hi,

 

I've worked in a few theatres and have noticed that a lot of people uses a scroller or a colour wheel with a black gel etc...to shutter of the projector i.e. even when a projector is outputting black there is still light.

 

Well I also have this problem at work, and at the mo I'm designing a simple shutter controlled by DMX, which is attached to the outside of the projector.

 

I was wondering if anyone might be interested in a device like this, if there is a need for it, I might consider making them to sell, would anyone be interested in one, how much would you recon ppl would be willing to spend on one?

[peter]

I think the main problem with shutters like these is that they're not integrated with the projectors - a few considerations for you:

-Internal power supply, with some form of 'in' and 'thru' power - so you can provide both with hard power from the same source.

-What apature size? This will depend what market you're going for - 2,000lumen projectors will have smaller lenses than 10,000 ones, so perhaps a range of products would be required.

-Would a fade be achieveable, or just a blackout/open white (such as the 'CD-tray with blackwrap' produces)

-How would you mount the shutter to the projector? At the moment, most of these are mounted with a bodge job of cable ties, ratchet straps etc - obviously a more reliable solution would be better, but with the huge range of projectors available these days, it would be complicated to produce a 'standard' mounting.

 

Have a search of the site - there are loads of topics relating to blacking out projectors, although most refer to bodge solutions.

 

Good luck

 

 

 

Peter

[Gareth A]

Whitelight were producing something last year for this. Not sure if it was a cosha sale item or something that they made for that job, but it consisted of a DMX card, a small motor with stops and a fin on the front. Very simple design, changed the size of the fin dependent on lamp size and was run for a lx desk as part of the plot.

[wilcoxjnr]

Pani make a DMX controlled grayscale glass dimming shutter for their large format slide projector which can work well for this application. Can't seem to find it on the website though...

[Benj]

There is also this guy, but this is shockingly expensive at 225euro! We ended up using a cd-rom drive. He also does DMX controlled DVD players which I had never seen before.

[3guk]

How did you manage to use a cdrom drive ?

 

Im always interested to hear and see how other people shutter projectors.

[timmiddleton]

see http://www.blue-room.org.uk/index.php?showtopic=4434

 

I've just finished my cd-drive version and I just used the info on the page above

[3guk]

http://www.wahlberg.dk/video/shutter.htm

 

Bloody hell they dont come cheap do they ?

[timperrett]

I am just about to start work on a theatre projection solution.

I would be interested to see what solutions you have come up with as I may need some solution of the nature of which you are talking.

 

On the Barco projectors, there are fitted shutters which are operated via the remote hand set, yet they still kinda 'clunk'/'click' shut and they still don't seem to have fixed this noise for some odd reason - even in Woman in White, the shutters from the G10s FOH can be heard shutting from the circle (if you are listening!)

 

If you can design a cost effective solution, there may possibly be a market, espcially with the recent trend of projection within performance.

[sverrir_d]

Hi,

 

I'm using the Dolby ScreenTalk system at the cinema I work for. It uses a douser to cover the lens on the projector when not projecting subtitles, when the film is running, the douser opens and closes every time a subtitle is being projected. My problem is that the projector is projecting added light (is supposed to be black) on the screen, and because the douser is moving you can easily see the "black" light frame from the projector every time the projector is projecting sutitles on the screen! As you know, the LCD controls the light trough the projector just like a LCD monitor. I once saw a device which can be placed in front of the projector to control how much light you want from the projector! But where did I see it, can't remember! This is what I realy need now, because seing this gray frame on the screen is terrible! If you know where to find this device, let me know, thanks!

 

www.selfossbio.is

[Tomo]

I'm guessing you are wanting something more like a vaned followspot dimmer shutter - the operation of these depends heavily on the focal planes of the optics, but as you're projecting a sharp image they should work ok in front of the lens.

 

AC Lighting have a few in their bargain basement - one of them is here. (requires external PSU)

 

They are available in both DMX/analogue controlled and manual - obviously the manual ones are considerably cheaper, but somebody has to push the lever whenever you want to change brightness!

[henny]

.

My problem is that the projector is projecting added light (is supposed to be black)

 

there's no real way round it , apart from going DLP , and the newer ones than that, (dlp = lots of little mirrors on a chip that the light bounces off or not , on the newer ones they have covered all the bits behind and around the mirrors on the chips with a photon absorbing coating , giving a better black)

 

 

ian

[Tomo]

If you're annoyed by the extra non-black during projection, (ie shutter open) then the only choice is to find a projector with a large contrast ratio.

I believe standard 70mm film is somewhere around 1000:1, so you probably want a projector that is at least as good as this, preferably better.

 

Of course a lot depends on the difference in brightness of the two projectors

 

DLP is the way to go for this - my manager and I bought one for the ship at ~1200:1 (claimed) which was about the best I've seen in terms of contrast in domestically available units. Can't remember the brand name unfortunately - Os-somethingorother I think.

 

However, DLP isn't 'better' than LCD as such. I found that it is similar to the difference between colour laser printing and colour inkjet printing.

 

DLP does blocks of colour brilliantly - very bright, hard colours, and very deep blacks - but it isn't very good for photographic work for that reason.

LCD colours are generally a little softer which makes it much more suitable for photographs. They usually give more greyish blacks due to the lower contrast.

[sverrir_d]

Thank you for your quotes, do you know about any projectors that emits minimium light? I'm currently using a Christie LX37. Do projectors with high contrast ratio emit less "black" light, rather than the ones with less contrast ratio?

 

Shall I go for Barco projectors or?

[Tomo]

Do projectors with high contrast ratio emit less "black" light, rather than the ones with less contrast ratio?

<{POST_SNAPBACK}>

In a word, yes (ish) - it's the ratio between full white and the darkest black the projector can do.

 

Higher gives darker blacks

 

However, two projectors with the same ratio but differing brightness will give different darkness of black, simply because it's measured as a ratio of brightest to darkest.

 

When it comes to recommending a particular model or brand, I'm not qualified as I've mostly used domestic units!

The best advice I can give is that you try out a few projectors that are within your budget, and see if you can borrow the shortlisted units for a couple of days to try out in your venue.

Seeing as you're looking at a $5000-plus unit, a lot of places should be happy to let you do that.

 

However, there may be another way!

Now that I think about it further, you may be able to physically shutter your existing projector so it's only able to illuminate the part(s) of the screen where subtitles fall.

Place some suitable opaque material in front of the lens, beyond the crossover point in the beam, and carefully position and shape it so you get only the area you want.

 

You should be able to try this out with some pieces of cardboard - so only cost is your time - and if it works satisfactorily then you can get some permanent steel made up for a small sum.

(Don't use cardboard as a permanent solution!)