dougalzeb Posted March 24, 2006 Share Posted March 24, 2006 Hi, I need a very cheap way of fading a signal from a dvd/vcr to a projector to leave a black screen. We can't really afford a vision mixer and don't need any effects or to mix to another video source. Any ideas or schematics around please? Cheers in advance. Link to comment Share on other sites More sharing options...
back_ache Posted March 24, 2006 Share Posted March 24, 2006 Hi, I need a very cheap way of fading a signal from a dvd/vcr to a projector to leave a black screen. We can't really afford a vision mixer and don't need any effects or to mix to another video source. Any ideas or schematics around please? Cheers in advance. Get a friendly script kiddie to write somthing for your pc that through the projector serial port slowly turn the brightness down to nought and back up again Link to comment Share on other sites More sharing options...
gingertom Posted March 24, 2006 Share Posted March 24, 2006 Dependant on environment, I find that even a black screen from the video source can still give out a relatively large (or distracting) amount of light from the projector. If what the OP wants is a mask for the projector lens, then there are many ways to achieve this. (From a piece of Litho on a string, to various Solenoid and DMX controllable affairs). The best I've found recently have been: A CD drive form an old computer in a skip, and some tinkering... and a handy ASM.Or more to my shame, an old set of semafores! (sp?) Link to comment Share on other sites More sharing options...
BenWall Posted March 25, 2006 Share Posted March 25, 2006 One way I have seen this achieved (at uni) is to put a scroller in front of the projector lense with a dark gel somewhere is the scroll (don't ask me what colour!), when you want to fade to black you just scroll to the dark colour all most creating a 'wipe' effect as the gel passes in front of the lense until it is totally black! This works really well... but it depends on whether you have a scroller and controller available, if you do then its a free effect (apart from the pain of having to tape the new scroll together, and potentially having to buy new gel and the special tape to join the gels.... OK maybe not really cheap, but fairly <_< ) HTH, Ben. Link to comment Share on other sites More sharing options...
mac.calder Posted March 25, 2006 Share Posted March 25, 2006 Another way would be to get a gobo rotator and use a pair of polarised lenses. It works really well once you set it up correctly. Link to comment Share on other sites More sharing options...
Jivemaster Posted March 25, 2006 Share Posted March 25, 2006 Projector black isn't really BLACK so you will need a moving shutter. A card or metal edge that can be controlled over the beam. Move it by levers and string, DMX and PICs and servos or Model RC servo and PWM train from a maplin servo tester. All depends on what you have to hand already to keep the cost down and efficienct up. Link to comment Share on other sites More sharing options...
Pete McCrea Posted March 25, 2006 Share Posted March 25, 2006 It might be worth to OP clarifying whether they need a total black out (Shutters/Filters/CD drawers/Small child with piece of cardboard) or simply wants to fade the video out and not have the horrible blue screen and OSD options shown. Both are relatively easy to achieve. Link to comment Share on other sites More sharing options...
back_ache Posted March 25, 2006 Share Posted March 25, 2006 Another way would be to get a gobo rotator and use a pair of polarised lenses. It works really well once you set it up correctly.I like this idea, you could even get away with one lense if it was an LCD projector Link to comment Share on other sites More sharing options...
Dweeks Posted March 26, 2006 Share Posted March 26, 2006 In a recent production, I had to switch between a DVD feed and a live camera feed, and used a Camlink Vision 500 video processor. They're dead cheap, but the video output allows you to fade to black, switch between sources, and fade back up. Avoids the bluescreen issue, and dirt cheap (£20 on ebay at the moment) Link to comment Share on other sites More sharing options...
wycome5 Posted March 26, 2006 Share Posted March 26, 2006 Could you not just lower some black material infront of the projector to stop it projecting? Link to comment Share on other sites More sharing options...
jcgoldcoast Posted July 25, 2006 Share Posted July 25, 2006 How about chucking the video into an editing program (something as simple as iMovie would do) and add a fade to black at the end of the video? Link to comment Share on other sites More sharing options...
mumbles Posted July 25, 2006 Share Posted July 25, 2006 Except this will still give you projector black, as jivemaster said earlier. At uni, we used a cd drawer, which we activated from the flys gantry, by touching wires against a battery. But this will still give you a slide across the screen, instead of a fade. Link to comment Share on other sites More sharing options...
Ben Langfeld Posted July 25, 2006 Share Posted July 25, 2006 How about a motorised iris, if you can buy one/knock one up? Link to comment Share on other sites More sharing options...
MarkPAman Posted July 25, 2006 Share Posted July 25, 2006 Most of this thread is about four months old. However: What about the CD drawer thing, but with tapered "fingers" attached. Not tried it, but should be smoother than a sharp edge. ;) Link to comment Share on other sites More sharing options...
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