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Title: Redundant Projectors?
Post by: Kyle Malenfant 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.
 
Title: Redundant Projectors?
Post by: Kyle Malenfant 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.
Title: Re: Redundant Projectors?
Post by: Sean Hayes 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
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant 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?
Title: Re: Redundant Projectors?
Post by: Jano Svitok 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? (http://www.srslight.sk/index.php?index=product&product=Projector_shutter)
Title: Re: Redundant Projectors?
Post by: brian maddox 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....
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant on April 23, 2013, 03:50:06 pm
This? (http://www.srslight.sk/index.php?index=product&product=Projector_shutter)

Very cool!  Any experience using it?
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant 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.
Title: Re: Redundant Projectors?
Post by: James Feenstra 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
Title: Re: Redundant Projectors?
Post by: Tom Bourke 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!
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant 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.
Title: Re: Redundant Projectors?
Post by: Brad Weber 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.
Title: Re: Redundant Projectors?
Post by: Brian Jojade 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.
Title: Re: Redundant Projectors?
Post by: Matt Tudor 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.
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant 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.
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant 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.
Title: Re: Redundant Projectors?
Post by: Jano Svitok on April 24, 2013, 09:49:39 am
Very cool!  Any experience using it?

No experience, I just saw it on their page.
Title: Re: Redundant Projectors?
Post by: Brad Weber 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.
Title: Re: Redundant Projectors?
Post by: Tom Bourke 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. 
Title: Re: Redundant Projectors?
Post by: Mac Kerr 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
Title: Re: Redundant Projectors?
Post by: Kyle Malenfant on April 27, 2013, 02:52:43 am
This is SOP in my world, but it seems unlikely that most shows could afford that level of redundancy. 

Mac

That is a wonderful luxury to have, though the more high-profile your event, I gather the more important it is to have redundancy at that extreme.
Title: Re: Redundant Projectors?
Post by: Ryan C. Davis on April 27, 2013, 02:59:04 am
...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.

This was my thought as well. Don't know if you're using a control system of any kind but pretty much any commercial projector worth a damn has rs232 or ethernet control, you could even run a single command from hyperterm or similar. With most commercial projectors you can even address them so you could feed once daisy chained serial cable to all of them and only the unite with the address you specify will respond to the unmute command.

Ethernet commands are very close to the same idea but I don't think you can use hyper term? maybe just a commanf prompt I don't know but the rs232 version would be easy for sure.
Title: Re: Redundant Projectors?
Post by: Gareth Marsh on April 29, 2013, 05:14:22 am
This was my thought as well. Don't know if you're using a control system of any kind but pretty much any commercial projector worth a damn has rs232 or ethernet control, you could even run a single command from hyperterm or similar. With most commercial projectors you can even address them so you could feed once daisy chained serial cable to all of them and only the unite with the address you specify will respond to the unmute command.

Ethernet commands are very close to the same idea but I don't think you can use hyper term? maybe just a commanf prompt I don't know but the rs232 version would be easy for sure.

I guess this comes down to the importance of the show again, but in most cases I would rather see the image get dull than have the entire image drop out until it could be switched over. Then again double stacking projectors is very familiar to me and I use projectors that can do this well so correct alignment is less of a consideration.

As a whole system it is quite rare to have a system that has full redundancy - even with control and playback backups unless you have multiple inputs going to your display devices you will still have a matrix or similar to do the switchover unless you want to have to transfer over to an entirely new system if you have a fault. I have even had a projector fault in a way that it was flashing the image continuously and the whole control system was jammed from the same issue - the only solution here was to pull the power - thankfully this was pre show, as no control solution would have helped here.

Situations like that encourage the idea of having 100% separate power and signal flow to the individual projectors that terminate to a place that you have easy access to. This is not always possible, but I do it wherever I can.


-Gareth
Title: Re: Redundant Projectors?
Post by: Ryan Kucharo on December 28, 2013, 04:13:05 pm
I know this is an older post and your event is done , but I noticed no one went into much detail about projector stacking.  In particular NEC offers projectors capable of doing this.  Check out this YouTube video: http://www.youtube.com/watch?v=NarilvwH4fk
Title: Re: Redundant Projectors?
Post by: Luther Bell on March 08, 2014, 08:33:01 pm
Just out of curiosity, what projectors were you using?  A good chunk of recent projectors have "Cornerstoning" and it is a really converging friendly feature (converging is the technical term for lining up projectors, whether it's the 3 gun Barcos or stacks of them now-a-days).   It's better to screw around and get in the habit because it's a handy skill to have.