Film-Tech Forum ARCHIVE: Portable digital projector that will work at a drive-in

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Posted by Justin Hamaker (Member # 2165) on 10-23-2008, 03:02 PM:

I'm hoping someone might be able to give me some direction on this. I'm working on a special event at our drive-in that would require a digital projector.

The throw from the projection room is about 400'. I know that is way too long for any consumer grade projector. But I'm wondering if anyone knows of a commercial projector that might work. Alternately, we might be able to place the projector out in the field as long as it can run off 110v.

Any thoughts would be appreciated. Also, if you know of some place on the West Coast (ideally in the Bay Area) where such equipment can be rented, that would be great.

Posted by Mark Gulbrandsen (Member # 72) on 10-23-2008, 10:50 PM:

Well, some of us know that any projector IS portable... [Eek!]

But nothing like that exists that can run off single phase 120 volts with sufficient lamp power to light a drive in screen. You'd need a projector with a 6kw lamp minimum and three phase 208VAC to power the projector. Lenses would be another problem all together!

Mark

Posted by Cameron Glendinning (Member # 3516) on 10-24-2008, 04:44 AM:

Firstly how big is your drive in screen?
Next question what sort of quality is required, is it a DVD powerpoint or 2k? 4.3, 16.9 or scope?

Posted by Bill Gabel (Member # 1105) on 10-24-2008, 09:56 AM:

quote: Justin Hamaker
where such equipment can be rented

What's you budget for rental?

Posted by Justin Hamaker (Member # 2165) on 10-24-2008, 01:14 PM:

I'll have to check on the screen size. If it helps, I can tell you the scope picture fills the screen side to side and leaves about 1' top and bottom.

I don't know what the budget is. At this point I'm more concerned with finding equipment that will work.

Posted by Sam D. Chavez (Member # 1841) on 10-24-2008, 02:57 PM:

Justin,

There are a number of rental outfits in the Bay Area and Sacramento but like us here on film-tech, they are first going to ask you all the same questions; screen size, power available, throw and size of your wallet.

Panasonic has some very bright 3 chip DLP projectors and I believe they will run on a 20 Amp., 110 Volt circuit.

You'll never get even minimally acceptable light level without a real screen surface and frame so unless you can place the projector close enough to a for real screen so an in stock lens can be used, tell your boss to fuggedaboutit.

Posted by Monte L Fullmer (Member # 2797) on 10-24-2008, 02:58 PM:

What wattage is your bulb in the lamphouse?

Then digital will require almost twice the wattage to fill the same screen since the light has to bend, and reflect off the arrays just to get the light out through the lens. It's not like film projection where light is a straight shot to the screen - to get the most light out..

Light doesn't like to be reflected for it loses so much luminance when it's either bent or reflected..

And, you definitely need that 3ph/208 to run such a device.

good luck in your search anywhos - Monte

Posted by Bill Gabel (Member # 1105) on 10-24-2008, 03:11 PM:

The people we use on the West Coast their Christie Roadster digital projectors (5000 to 20,000 lumens) will run you $1,750.00 to $4,500.00 a day on rental depending on the model. The Lightning 28sx (14,000 lumens) rents for $3,500.00 a day.

Posted by Scott Norwood (Member # 30) on 10-24-2008, 03:20 PM:

I don't know how true this is, but I've been told that 10k lumens is roughly equivalent to a 2kw xenon with 35mm (presumably this implies a standard 2-blade shutter, f/2.0 lens, etc., etc.). Subjectively it looks similar (maybe slightly brighter than film), all other things being equal.

Posted by Julio Roberto (Member # 4976) on 10-24-2008, 07:50 PM:

Perhaps something like the Sanyo PLC-XF47 with a long throw lens (like i.e. LNS-T01 or LNS-T03) would do.

It will do 120v (about 1700w, IIRC) and put out about 15.000 lumens.

It can often be bought for around 19k, just to give you an idea of how much rental could be.

With the LNS-T01 lens, it should give you an aprox. 40' by 53' image from a distance of 366 feet at 7fL on a 1.0 gain screen.
With the LNS-T03 zoom lens, it should give you a 35' by 47' image from 421' distance at 7fL on a 1.0 gain screen.

There are other models by Sanyo, Panasonic, Eiki (LC-XT5 runs at 200v single phase, so you could just use a step-up transformer, at 1800W), Sony, Christie, Digital Projection or Barco that could also, perhaps, do the job. Also some old machines by JVC, perhaps.

Posted by John Hawkinson (Member # 1135) on 10-24-2008, 08:26 PM:

So, Justin, what's your 35mm lamp like (wattage), and what's your 35mm focal length?

It seems odd to me that you can have 120V in the field but can't manage to get 3-phase...

--jhawk

Posted by Justin Hamaker (Member # 2165) on 10-24-2008, 08:51 PM:

The 35mm is a 4K bulb in a Christie lamphouse. The focal length is about 400'. We can do 110v in the field by running an extension cord.

Just to be clear, this is for a one time only event so a 'Micky Mouse' option would be ok.

Posted by John Hawkinson (Member # 1135) on 10-24-2008, 09:00 PM:

No, the throw is 400'. The focal length is a characteritic of your lens, like 120mm or what-have-you. If you don't know your screen size, the combination of throw and focal length with let us calculate it [Smile]

(Err, tell us whether its your scope or flat lens)

No reason you can't do extension cords for 3-phase...

--jhawk

Posted by Julio Roberto (Member # 4976) on 10-24-2008, 09:46 PM:

Well, if you want something cheaper that could save the day (at around $10k street prices) you could try the EIKI LC-X7 or the Sanyo XF42.

It should give you about a 7fL brightness 27'x36' image on a 1.0 gain screen at about 321' throw distance with the LNS-T03 lens option.

You really shouldn't go much below that for your intended location.

But if you can get closer to the screen (about 60ft), you could just rent 2 or 3 identical small projectors with standard lenses and use them simultaneously to overlap the screen (make sure they have lens shift option and digital keystoning correction and place them as close as possible).

I.e., a couple of $4500 Sanyo PLC-XT35 in dual projection should give you about 8fL to a 28' by 37' 1.0 gain screen from 80 feet away with the standard lenses.

Other alternatives, like a single $4500 NEC NP3150 or EIKI EIP-5000 could give you 30'x40' image at 6fL (on 1.0 gain) from around 60' on the standard lens. If you can find a focal length convertion lens (teleadaptor) to rent for the NEC's diameter, you could extend that distance (usually by 50%, so about 90') with an aprox. 15% loss of light and some small loss in image quality.

Posted by Mark Gulbrandsen (Member # 72) on 10-24-2008, 10:47 PM:

quote: Justin Hamaker
We can do 110v in the field by running an extension cord.

You can also run two extension cords connected to two different circuits on different phases and have 230 volts just as easily. Just be sure to properly ground the piece of equipmeny no matter what voltage you decide to use... Safety First, especially outdoors!

Posted by Justin Hamaker (Member # 2165) on 10-24-2008, 11:38 PM:

quote:
The focal length is a characteristic of your lens, like 120mm or what-have-you

I'll find out tomorrow and get back to you.

Mark, I had never heard that about using the two extension cords. Any idea how I ensure I've got different phases? Even if we didn't use this solution it would certainly be good information to know. I could foresee the possibility of maybe using a popcorn machine outside if we ever had a flee market or something.

Posted by John Hawkinson (Member # 1135) on 10-24-2008, 11:52 PM:

Just measure the voltage (hot-to-hot, i.e. small prong to small prong) on the two circuits.

If the voltage is ZERO, you have the same phase.
If the voltage is 208V, you have two differenct phases.
If the voltage is 120V, you have screwed up (phase-to-ground voltage).
If the voltage is 240V, something is whacko.
if the voltage is 277V or higher, seek professional help.

If you're running 100' extension cords, you might find the voltage sags noticable (perhaps from 208 down to 200 or 190) when you actually power up the projector. That could well be a serious problem.

--jhawk

Posted by Monte L Fullmer (Member # 2797) on 10-25-2008, 12:09 AM:

quote: Justin Hamaker
Mark, I had never heard that about using the two extension cords.

It's an old welder's trick when they need to use their welder that needs 220vac in a place that hasn't the convienence of a 220v socket.

Thus, they take two long 10g cords and attach the hot to each terminal on the 220v,4 lug socket.

Tie the neutrals and grounds to their respective terminal in the socket, and on the other end of each cord, put a standard 120vac plug on it.

Then plug each cord in a socket where each socket is on a different breaker in the panel and "voila!" 220v single phase to run their welders.

Posted by Mark Gulbrandsen (Member # 72) on 10-25-2008, 09:06 AM:

quote: Monte L Fullmer
It's an old welder's trick when they need to use their welder that needs 220vac in a place that hasn't the convienence of a 220v socket.

Well, I may be old but I'm not a welder... I just used to do this alot for location film equipment rentals. We actually keep a setup with two extension cords made from 10/3 SO and a box with a 230 volt outlet all tied together at CLACO for location rental work. Its a heavy beast! Its pretty common in the rental world...

Posted by Stephen Furley (Member # 1277) on 10-25-2008, 01:04 PM:

quote: John Hawkinson
Just measure the voltage (hot-to-hot, i.e. small prong to small prong) on the two circuits.

If the voltage is ZERO, you have the same phase.
If the voltage is 208V, you have two differenct phases.
If the voltage is 120V, you have screwed up (phase-to-ground voltage).
If the voltage is 240V, something is whacko.

Or it's a domestic type centre-tapped single phase supply? I suppose you'd be unlikely to have that at a drive-in, but you might elsewhere.

quote: John Hawkinson
if the voltage is 277V or higher, seek professional help.

You really like to make your electrics complicated over there, don't you! [Roll Eyes]

quote: John Hawkinson
If you're running 100' extension cords, you might find the voltage sags noticable (perhaps from 208 down to 200 or 190) when you actually power up the projector. That could well be a serious problem.

--jhawk

Could you run two cables connected in parallel to reduce the resistance, or would your regulations not allow that? I'm not sure if it would be allowed here. The way you'd do that sort of thing here would be to simply run a cable of whatever size was required, with a pin and sleeve type connector on the end of it, 3-pin blue for single phase, 5-pin red for three-phase. No question about what Voltage you need. If you don't have a suitable supply available you hire a generator which in small sizes, up to 125A, use the same type of connectors.

120, 208, 240, 277, 347, 480, 600. Wye, delta, centre grounded, corner grounded, ungrounded, dozens of different NEMA sockets... We'd have electricians jumping out of windows if they had to cope with the number of different Voltages and systems that you have over there! [Confused]

Posted by John Hawkinson (Member # 1135) on 10-25-2008, 07:30 PM:

It's always dangerous when you try to be comprehensive, especially for the point of injecting humor. Yes, 240V shows up in the US for a single center-tapped phase (split-phase), which is typically only for residential service.

And if you have single-phase equipment, 240V might be acceptable to the equipment (check the nameplate!), or more scarily, the voltage drop (under load, only!) might bring it down to something acceptable, which is a dangerous way to go as well.

(We have some Irem single-phase rectifiers that are running through boost transformers at around 240V where they perform much better than at 208V. Their nameplate voltage is 220V, and they have trouble producing sufficient voltage to strike 2K lamps when fed 208V...)

Running two phases from different single-phase circuits is a temporary jerry-rigging that, if permitted at all by code, qualifies as a temporary installation. You can parallel two cables as temporary installation as well, yes. Depending on what kinds of currents we're talking about and what gauges of wire, it might or might not be reasonable. (But, of course, at that rate you're probably better off just renting the higher gauge cable from a local theatrical supply house.) Several of these answers are probably only things that should be done by people with more experience than I think Justin has...

For a temporary installation, to combat voltage drop, you could also use a boost transformer. Generally this is a no-no, because then you have voltage that significantly with the load, which is not a terribly safe condition. But if your load is constant and you're aware of it, and it is a temporary installation, it is not so terrible.

--jhawk

Posted by Stephen Furley (Member # 1277) on 10-26-2008, 05:32 AM:

So, what sort of supply would you typically be asked to supply for a temporary installation for a large outdoor screen? Somebody suggested that a 6kW lamp would be appropriate; given less than unity power factor, losses and ancillary equipment I would guess that guess that you'd be looking at something like a 10-12 kVA supply. Would this generally be 208/120V three phase Wye? If so, then this is basically a half-Voltage, higher frequency version of what we have here. I would guess that you wouldn't try to send a supply very far at these Voltages, and that if you had an event any great distance from an existing supply, say in the middle of a park, then you would probably use generators.

Would the lamp rectifier be fed with 208V three phase, and everything else be 120V single phase? A 20A supply might do this, but it would be a bit tight, and I think the next size up is 30A, so I'm guessing that you'd put in 30A three phase 208/120V Wye.

How would you terminate the temporary supply at the remote end, would it be hard wired into a distribution panel, or plugged in?

Posted by Ben Wales (Member # 92) on 10-26-2008, 07:23 AM:

quote: Mark Gulbrandsen
You can also run two extension cords connected to two different circuits on different phases and have 230 volts just as easily.

That sort of run and the Voltage/Amps required for a good size Digital Projector, I would advise hire in a Generator, far more reliable than local 2 phase power.

Posted by Alan Gouger (Member # 543) on 10-26-2008, 09:11 AM:

Using a Navitar telephoto screenstar lens in front of the projectors primary may give you the throw you need. These are high quality lens that do not degrade the image.
http://presentation.navitar.com/pages/product_information/screenstar_projection_conversion_lenses/overview.cfm

Posted by Frank Angel (Member # 248) on 10-26-2008, 10:20 PM:

It might be easier to just stack smaller units to get your brightness rather than looking at super projectors that probably will be more costly to rent and more difficult to power. Stacking is routinely done and you rental houses have hardware that makes stacking fairly foolproof. This might be a better way to go.

Posted by Barry Floyd (Member # 385) on 11-18-2008, 12:16 PM:

Justin,
We did a similar thing at my drive-in about 2 years ago. I had a guy call me who wanted to propose to his girlfriend and put a video on screen of their dating relationship, well wishes from friends and family, etc.. He was a film student at Watkins Film School in Nashville, and he told me he had a video projector that he could use as long as I had an extension cord.

When I met him out at the theatre one night after work, and he pulled out this little conference room table video projector, about the size of a small VCR. I was thinking to myself ... NO Way was this going to work as we were standing 275 feet away from the screen. He plugged it in and I must honestly say... I was AMAZED. It actually worked. Albeit, the mismatched lens made the picture about twice the size of the screen, and the picture was a little dark... but with about twice as much light and the right lens... it definetely had potential for something. (Advertising slides, private rentals, etc.) I anticipated the guy would leave the theatre with his "bubble burst" because his little dinky projector would be the equivalent of shining a flashlight on the screen from the back row.

He played part of his tape, and I walked up to the bottom of the screen expecting to see pixels the size of basketballs.... it was perfect.

This wasn't some fancy digital cinema thing, this was an ordinary business-style conference room table video projector.
I believe the name brand was "In-Focus", and the model number was the "Screenplay 5000"

We pulled 2 100 foot extension cords from the ticket booth and ran the projector from the roof of his car. Instead of the projector being back at the building, it was probably only 100 feet from the screen.

Posted by Justin Hamaker (Member # 2165) on 11-18-2008, 07:51 PM:

Thanks everyone for the input. I'll have to remember the extension cord trick for future reference.

The people wound up having their film transfered to 35mm and we just ran it through the projector. But the digital information is good to know in case it comes up again.