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Author Topic: Redundant Projectors?  (Read 7949 times)

Kyle Malenfant

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Re: Redundant Projectors?
« Reply #10 on: April 23, 2013, 04:56:28 pm »

Both projectors should be the same make/model.  They also need to be rigidly mounted one over the other in the same orientation.  I have seen this done with projectors that required a fork lift to move!

So it seems then that it would be more efficient to focus both projectors, yet shutter one (motorized or cardboard) as a backup in the event of a lamp failure. Having both projectors running simultaneously appears to be outside of the scope of my experience.
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Brad Weber

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Re: Redundant Projectors?
« Reply #11 on: April 23, 2013, 05:22:44 pm »

great advice on the cardboard. And thanks for the input on the lamp being the weakest link...that's exactly the experienced opinion I need.
Many modern projectors use multiple lamps and let you set the lamps up to operate simultaneously for higher output or operate on less than all the lamps at a lower brightness for either increased lamp life or redundancy.  I really like dual or quad lamp projectors for this reason, you can run them as high brightness and a lamp failure simply means a less bright image or run them at a lower brightness in a redundant mode with automatic switching of lamps if a lamp fails.

I'd also watch cardboard or anything flammable directly in front of a high brightness projector lens, maybe try to use something less flammable or leave some room.
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Brian Jojade

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Re: Redundant Projectors?
« Reply #12 on: April 23, 2013, 06:27:07 pm »

+1 on the problem with flammable materials in front of the lens.  You're going to have a fair amount of heat buildup there on high output projectors.  The last thing you want to see is smoke!

Whenever you are working in a high value job, redundancy in gear is very important.  Anything mission critical should have a backup in place.  How mission critical, and how long you can live without the gear in the show will determine the steps needed to set it up.  In the case of the projector, if you set up and focus two, but one winks out, if you have the second one running with a shutter, a simple flip of the shutter will get you back on.  But that means you're burning the lamp the whole show regardless if you need it or not.  If it's less critical, you can simply have the 2nd projector there and focused, and if something happens, you power up projector two and have image back within a minute.

It all really depends on the budget.
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Brian Jojade

Matt Tudor

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Re: Redundant Projectors?
« Reply #13 on: April 23, 2013, 06:48:14 pm »

I have a university commencement coming up next month and this is the first year they are adding IMAG to the ceremony.  Two HD projection screens flanking the stage...

It was recommended to me from a colleague that I should run two projectors on each screen, 100% overlapping the images for redundancy purposes in case one projector fails.  Is there a certain devices needed to merge the images or just keep the projectors as close as possible and line up the images, keystone, zoom, etc?

Is this really necessary?  To keep one as a redundant backup, logic would tell me that each projector then should be on a different AC circuit, with a separate video feed, from a separate switcher?  Am I over complicating things?  The projectors will be rigged 25ft. up from the house I beams (house engineer signed off on the rigging points) and fixing a failed projector mid-show is not feasible.

Thanks for the input.

<edit> Moving to AV forum...sorry, accidentally posted here in the basement. Mods you can delete the post from this page.

We used to double up projectors to get a brighter image. It's certainly possible, but took forever to get all the variables properly aligned. You're better to get the image pretty close by physically moving the projectors before you rely on keystone though, because keystone and zoom can sometimes skew the image slightly. Then only parts of the screen line up at once. Don't know if we ever got it pixel-to-pixel perfect. Much easier to do with projectors that have actual grid patterns for focusing rather than simple crosshairs, and lens shift is your friend. It's still a pain in the butt.
If you have the two images superimposed, then the audience is going to notice when one of the projectors fails anyway, because the image gets darker. If it were me I wouldn't worry about lining them up, and only use the backup after the primary failed. I would have the second projector standing by, warmed up, with video mute on. Then you don't have to worry about perfectly matching the images or having images of different brightness in the event of a failure. Just un-mute the backup and keep going.
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Kyle Malenfant

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Re: Redundant Projectors?
« Reply #14 on: April 23, 2013, 07:41:20 pm »


I'd also watch cardboard or anything flammable directly in front of a high brightness projector lens, maybe try to use something less flammable or leave some room.

Great heads up...safety first.
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Kyle Malenfant

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Re: Redundant Projectors?
« Reply #15 on: April 23, 2013, 07:46:21 pm »

Hard to comment on everyone's replies, but thank you so much for all the input.  It has been very helpful and I gather the consensus is to use both projectors, but shutter/block/etc. one to save myself the hassle of aligning them on the screen.
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Jano Svitok

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Re: Redundant Projectors?
« Reply #16 on: April 24, 2013, 09:49:39 am »

Very cool!  Any experience using it?

No experience, I just saw it on their page.
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Brad Weber

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Re: Redundant Projectors?
« Reply #17 on: April 24, 2013, 10:08:28 am »

Hard to comment on everyone's replies, but thank you so much for all the input.  It has been very helpful and I gather the consensus is to use both projectors, but shutter/block/etc. one to save myself the hassle of aligning them on the screen.
From a spare lamp module on hand to a multiple lamp projector to redundant projectors to a completely redundant system from source to projector, there are a range of options,  Which makes the most sense all depends on what is practical or available and how critical any downtime or reduction in performance would be perceived.  Will the event come to a stop or be considered a failure if the image drops in brightness or if a projector goes down even temporarily?  Or might a reduction in brightness, either from the start or as a result of a lamp failure, or temporary outage be acceptable?

Also note that lens optics change as they heat up, so whether it is a redundant projector or a shutter, if you use a second projector then for the best image quality you would want to set it up after it had been running some time and have it warmed up and ready to go rather than turning it on when something happens.
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Tom Bourke

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Re: Redundant Projectors?
« Reply #18 on: April 27, 2013, 01:26:03 am »

So it seems then that it would be more efficient to focus both projectors, yet shutter one (motorized or cardboard) as a backup in the event of a lamp failure. Having both projectors running simultaneously appears to be outside of the scope of my experience.
The gig with the really big projectors had them aligned and both on and in use for more brightness.  They also had redundant playback computers running synced.  One of the road crew had to monitor the computers and if something wend down he would hit a switch to transfer all projectors to the backup system. 
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Mac Kerr

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Re: Redundant Projectors?
« Reply #19 on: April 27, 2013, 01:29:58 am »

The gig with the really big projectors had them aligned and both on and in use for more brightness.  They also had redundant playback computers running synced.  One of the road crew had to monitor the computers and if something wend down he would hit a switch to transfer all projectors to the backup system.

This is SOP in my world, but it seems unlikely that most shows could afford that level of redundancy. The show I just finished had 8 21k panasonic projectors, but I think only 4 of them were fully on.

Mac
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