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» Film-Tech Forum   » Operations   » Digital Cinema Forum   » Extreme short throw projector (Page 1)

 
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Author Topic: Extreme short throw projector
Geoffrey Hudson
Film Handler

Posts: 12
From: grand rapids, mi
Registered: Jan 2013


 - posted 02-05-2013 02:52 PM      Profile for Geoffrey Hudson   Author's Homepage   Email Geoffrey Hudson   Send New Private Message       Edit/Delete Post 
Hello. I'm new to the forums. I must say I was pretty pleased to find this by accident. It seems a great resource for talking the nuts and bolts of theater operation! I work at Wealthy Theater, a 100 year old venue in Grand Rapids, MI.

Anyway, I had a projector question to put out here and see if any of you more experienced types might offer any feedback.

What we are trying to do is mount a projector from a lighting truss onstage to project on the cloth at the rear of the stage.... We're not exclusively a movie venue, people use the space for many things and sometimes we have need for this type of projection...

So we are talking about a throw distance of only 10' filling a visible space about 12' x 30.'

I've looked at a few extreme short throw projectors and am leaning towards the NEC NP-UM330W:
http://www.bhphotovideo.com/c/product/906909-REG/nec_np_um330w_np_u330w_lcd_wxga_3300.html

Does this seem like it would do the job or can somebody suggest a more suitable model? Any factors I haven't thought of?
I see the lenses on these short throw are noticeably different. So they'd hopefully be equipped for some Xtreme keystoning?

Any help is appreciated!

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Carsten Kurz
Film God

Posts: 3865
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 02-05-2013 03:04 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
What kind of projector would you use? Will it have to play regular cinema content under the same conditions as well?

- Carsten

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Geoffrey Hudson
Film Handler

Posts: 12
From: grand rapids, mi
Registered: Jan 2013


 - posted 02-05-2013 03:26 PM      Profile for Geoffrey Hudson   Author's Homepage   Email Geoffrey Hudson   Send New Private Message       Edit/Delete Post 
That NEC projector I mentioned was the one I am considering. Looking to get advice if I am on the right track.

Our stage has a screen that lowers at the front for cinema content.
We raise it to use the stage for live performance.
Sometimes there is a need for logos, powerpoint or video as accompaniment to be projected in the background during performances.
We have been using our main projector for this but it isn't ideal as we are coming from 70 feet away and are projecting onto the performers.
The idea with this 2nd projector is to put it on the lighting truss of the stage and project overhead onto the back of the stage.
Hopefully my explanation is clear. Maybe should have made a diagram...

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Richard Fowler
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From: Ft. Lauderdale, FL, USA
Registered: Jun 2001


 - posted 02-05-2013 03:59 PM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
I have used this type of projector for advertising (rear screen) in hotel lobbies and front screen for stage "video scenery". The trade off is fairly limited postioning of image to screen due to the lens designed to project at a 50 degree angle. Your 12 x 30 cyc would need three of these to cover the area widthwise.....get the lens chart and dimensional drawings and work up a shop drawing or rent one to check your space.

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John Thomas
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From: Northville, MI, USA
Registered: Sep 2011


 - posted 02-05-2013 04:51 PM      Profile for John Thomas   Email John Thomas   Send New Private Message       Edit/Delete Post 
Is rear projection out of the question?

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Geoffrey Hudson
Film Handler

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From: grand rapids, mi
Registered: Jan 2013


 - posted 02-05-2013 05:10 PM      Profile for Geoffrey Hudson   Author's Homepage   Email Geoffrey Hudson   Send New Private Message       Edit/Delete Post 
We are trying to project onto the cyclorama which is only inches from the stage back wall so rear isn't really an option.

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Mike Blakesley
Film God

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From: Forsyth, Montana
Registered: Jun 99


 - posted 02-05-2013 11:42 PM      Profile for Mike Blakesley   Author's Homepage   Email Mike Blakesley   Send New Private Message       Edit/Delete Post 
What about keystoning? You're projecting at a huge angle. Can a digital machine adjust for THAT much of an angle?

You could have a guy like our own Bobby Henderson in the crowd who would be very upset if his carefully designed logo was projected all distorted.

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Cameron Glendinning
Jedi Master Film Handler

Posts: 844
From: West Ryde, Sydney, NSW Australia
Registered: Dec 2005


 - posted 02-06-2013 01:27 AM      Profile for Cameron Glendinning   Email Cameron Glendinning   Send New Private Message       Edit/Delete Post 
I use short throw 720p wxga projectors for outdoor cinema all the time. They have a fixed lens so positioning is not flexable and the projector MUST be exactly in the center (near the top or bottom of the screen) or noticeable distortion is obvious. Optoma have 3 short throw models available with 0.3, 0.52 or 0.7 options. 1 being the width of the screen. 3100 lumen s will just fill a 25 x 14ft screen in darkness with a reasonable quality of brightness.

Your cloth is not the native shape for most computer or HD video and needs a more realistic 16.9 ratio, which would be closer to 20x11ft. If your lighting truss is close to the top of the "screen" the image will not need much keystone correction.

With a 0.52 lens with a 10ft throw, you will produce a image close to 20ft wide image that's about 11 ft tall when keystone is set correctly. Computer images can be a bit taller than a dvd. 16.10 ratio

With the smaller image depending on the screen/ cloth and its gain you will have some extra brightness which will help with ambient light.

Different settings in the menu dictate the real lumen output, usually movie is the darkest, presentation the brightest.

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Carsten Kurz
Film God

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From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 02-06-2013 07:29 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
30' wide with a 3300lm projector would probably be enough for non-cinema content in a dark auditorium.

Under stage light conditions, it is definitly not enough. You should go towards something above 5000-6000 lumens.

Very often, dedicated short throw projectors have no lens shift. With 10% keystone correction like on the NEC, that could be insufficent. Plus - with a large amount of electronic keystone correction, you not only lose image quality, but also light (in the corrected corners).

Not a good idea. Look for projectors WITH lens shift., and optional wide angle lenses (and check wether lens shift can be used with that lens at all).

Is there a tight budget for this? At 1.300US$, your options are very limited.

- Carsten

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Richard Fowler
Film God

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From: Ft. Lauderdale, FL, USA
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 - posted 02-06-2013 09:06 AM      Profile for Richard Fowler   Email Richard Fowler   Send New Private Message       Edit/Delete Post 
Depending on the set or lighting designer intent of effect you need enough lumens to counteract light spill / floor reflections. The smallest unit I use is 8000 lumen and have done stacked and blended displays at 24000 - 30000 lumen for a full stage treatment. 3300 lumen may be fine in your situation....best to do a mock up to see if you are satisfied. If your cyc is cloth more light is need versus a white PVC sheet. Recently we are getting more request to hang mini video projectors on electrical flylines for video effects on floors and set walls + cameras to catch a overhead view for dance companies.

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Geoffrey Hudson
Film Handler

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From: grand rapids, mi
Registered: Jan 2013


 - posted 02-06-2013 11:28 AM      Profile for Geoffrey Hudson   Author's Homepage   Email Geoffrey Hudson   Send New Private Message       Edit/Delete Post 
Thanks for all the great info everyone! Quite a few aspects I hadn't thought of.

We are not necessarily locked into a $1200 budget for this projector but wouldn't want to go much over say $1500.
This is a secondary use projector for special onstage situations. We are shopping for this in addition to a new main cinema projector (possibly a Solaria One) so the bulk of our budget will go to that and what's left for this onstage projector.

There are probably a few projectors or lenses that might do what we're looking for but there are so many options out there I don't even know how to narrow it down...
Was hoping somebody might chime in with something like "Oh yeah, we do exactly what you're trying to do! We use a _______ and it works great for us!" [Wink]

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Scott Norwood
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From: Boston, MA. USA (1774.21 miles northeast of Dallas)
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 - posted 02-06-2013 12:23 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Is there a reason why you con't use your normal video projector, perhaps with a different lens? Is it an issue of a steep throw angle from the booth or something like that?

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Geoffrey Hudson
Film Handler

Posts: 12
From: grand rapids, mi
Registered: Jan 2013


 - posted 02-06-2013 12:25 PM      Profile for Geoffrey Hudson   Author's Homepage   Email Geoffrey Hudson   Send New Private Message       Edit/Delete Post 
The issue with using our main projector is that you end up projecting on top of performers on the stage. The thought with having this secondary projector on the lighting truss is that then we're projecting over them.

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Carsten Kurz
Film God

Posts: 3865
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 02-06-2013 04:53 PM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
There is a site in german which allows you to search all current and previous projectors on the market by various aspects like brighness, projection geometry, etc.

That could reduce the enormous amount of projectors available to the few that may be of interest for you.

But I think you need to measure the stage very well and make a drawing of projection distance, image width, projection offset. And try to relax your constraints.

http://www.projektoren-datenbank.com/menu1/menue/sucheingabeprojektor.php?menue=22

Funny, when I feed a projection ratio of 0.3 to the search engine, it comes up with 41 hits - all with rear-projection mirrors, so bascially, all whiteboard projectors.

0.3 and a tight budget - nearly impossible. You should first try to rent one to see wether it is working at all.

- Carsten

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Jay Glaus
Expert Film Handler

Posts: 119
From: Pittsburgh, PA USA
Registered: Dec 2010


 - posted 02-09-2013 03:04 AM      Profile for Jay Glaus   Author's Homepage   Email Jay Glaus   Send New Private Message       Edit/Delete Post 
Don't know if this helps, and I'm fairly new to the digital end of projection, but didn't Barco just come out with a very small scale projector? Don't know if it would work or not and never priced it out.
Jay

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