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Author Topic: Redundant Projectors?  (Read 7886 times)

Kyle Malenfant

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Redundant Projectors?
« on: April 23, 2013, 10:59:23 am »

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.
 
« Last Edit: April 23, 2013, 12:03:01 pm by Kyle Malenfant »
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Kyle Malenfant

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Redundant Projectors?
« Reply #1 on: April 23, 2013, 12:03:27 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.
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Sean Hayes

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Re: Redundant Projectors?
« Reply #2 on: April 23, 2013, 01:39:32 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.

Kyle,
You are on the right track. Focus both projectors using a grid. It is very important to get the images perfectly aligned. This takes a fair amount of practice to be able to do this quickly. Send both projectors the same feed.
Needing more than one circuit depends on how much draw the projector requires. My guess is that if this is a high lumen projector you will want to have a single circuit for each projector. However, if this is not needed, I would not worry about finding two different power sources for redundancy. If your distro goes down, most likely so will the sound and lighting, thus stopping the show. However, it is a good idea to keep your switcher on battery backup. Just remember that you can only do so much to guarantee no failures within a budget.

One more thought... If you need two projector ONLY for redundancy, it might be easier to just shutter one projector rather than spend a lot of time aligning them.

Sean
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Sean T. Hayes

Kyle Malenfant

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Re: Redundant Projectors?
« Reply #3 on: April 23, 2013, 01:44:14 pm »



One more thought... If you need two projector ONLY for redundancy, it might be easier to just shutter one projector rather than spend a lot of time aligning them.

Sean

Thanks Sean.  At 25 ft up, if one is shuttered and the other fails, what's the best way to open up the shutter?  Ladder up to the truss?
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Jano Svitok

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Re: Redundant Projectors?
« Reply #4 on: April 23, 2013, 03:22:17 pm »

Thanks Sean.  At 25 ft up, if one is shuttered and the other fails, what's the best way to open up the shutter?  Ladder up to the truss?

This?
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brian maddox

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Re: Redundant Projectors?
« Reply #5 on: April 23, 2013, 03:40:47 pm »

Thanks Sean.  At 25 ft up, if one is shuttered and the other fails, what's the best way to open up the shutter?  Ladder up to the truss?

unless you need the extra brightness, i would definitely recommend using the second projector ONLY as a backup and shuttering it.

depending on the projector, it may have a 'mute' function that will shutter it internally.  there will sometimes be a small amount of light spill however.

you can get the professional shutter device shown above, but sometimes it's simpler to just rig a piece of dark cardboard or duvatyne using some gaff tape and a long string that can be used to quickly reveal the second projector.

also, this redundancy is basically used to insure against lamp failure, which is fairly common in large scale projectors.  redundant power, signal, and switching is nice and all, but by far your most likely failure will be the lamp....
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Kyle Malenfant

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Re: Redundant Projectors?
« Reply #6 on: April 23, 2013, 03:50:06 pm »

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Kyle Malenfant

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Re: Redundant Projectors?
« Reply #7 on: April 23, 2013, 03:53:32 pm »


also, this redundancy is basically used to insure against lamp failure, which is fairly common in large scale projectors.  redundant power, signal, and switching is nice and all, but by far your most likely failure will be the lamp....
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.
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James Feenstra

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Re: Redundant Projectors?
« Reply #8 on: April 23, 2013, 04:03:37 pm »

converging projectors should be doable from within the projector...all you'll really need is keystone, zoom and lens shifting capabilities. you'll definitely need the same grid projected from both projos at the same time

If you feed them both off the same DA you'll be alright in terms of signal...no sense in running a separate feed. If you want to be super safe about it, keep the DA on the ground and run a each on it's own circuit (Also located at ground level) so you can troubleshoot a potentially failed signal without actually going up to the projo.

Running them both at the same time won't be an issue, and will benefit you with additional brightness. This is done all the time for just that reason.

If they're not lined up exactly though, your image will turn out fuzzy
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Tom Bourke

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Re: Redundant Projectors?
« Reply #9 on: April 23, 2013, 04:51:46 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!
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