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Topic: 7000 Watt Lamphouse for DI, good idea?

Richard Greco
Phenomenal Film Handler

Posts: 1180
From: Plant City, FL
Registered: Nov 2003

posted 01-15-2005 01:39 AM

Well, my theatre is finally doing some major upgrades since new ownership. The first thing is that we are getting a 7000 watt lamphouse for our biggest screen. I'm not sure about footlamberts and such, but the booth is roughly 300-400 feet from the screen. My main concern is melting the film with the heat. We are currently using a 400 watt and there is much washout from external light sources. Is 24fps fast enough to not get melted running through this gate?

Also, we are getting 3 new sets of flat and scope lenses. Hopefully, aperture plates will be on the way and our presentation will be even better with no overlay onto buildings.

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 01-15-2005 01:42 AM

There is no way you are currently using a 400 watt bulb.

Go with a Christie SLC-45 console and burn 6000 watt lamps in it. (You will get more light than with a 7000 watt.) I've seen this in action at a drive-in and the result was amazing. (You can also see it on that Harry Potter drive-in bootleg video that is somewhere buried in the archives here.)

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Richard Greco
Phenomenal Film Handler

Posts: 1180
From: Plant City, FL
Registered: Nov 2003

posted 01-15-2005 01:52 AM

I meant 4000, sorry wireless keyboards can suck sometimes

Also, I don't have any control over what we are getting. I'm not sure what make the house is but I'll post as soon as I know.

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 01-15-2005 02:22 AM

..just have plenty of exhaust pulling all of that heat using those SLC-45 consoles with that 6K bulb. True, best consoles to use in this application.

I ran a D.I. 20yrs ago that we had 4K bulbs in Strong Futura III's(?)lamphouses behind MotioGraph AA's and using 6k reel changeovers. The Strong lamphouses were the right match with that cylinder shutter that MotioGraph uses being the light degrees was low to completely pass the cylinder paddles when opened. The distance from the bulb's arc to aperture opening was the same when we had the Ashcraft's 13.6mm rotators out there. The throw was 180 ft to a 90 x 170 ft screen. Scope pictures looked great and sharp.

7K bulbs is the maximum bulb usage with 35mm. Any higher, then the film can't take that heat.

-Monte

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Stephen Jones
Master Film Handler

Posts: 314
From: Geelong Victoria Australia
Registered: Jun 99

posted 01-15-2005 06:38 AM

Richard are your projector gates water cooled? as its recomemded that running lamps 4k and above the gate should be water cooled.I currently run 7K lamp in our biggest screen with no effect from heat at all but the gate is cooled with chilled water.Chilling water for 7k lamps and heat filters are recomended and make sure that your exhaust fans are rated for the extra heat that a 7k will generate and you should not have any heat problems with the film at all.You could try a 5k 0r 6k to see if they would do the job as they tend to do good hrs as a 7k is rated about 500 hrs service life (osram). Most drive-ins here us mainly 5k to 6k lamps with good results.

Steve

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 01-15-2005 08:18 AM

I agree on the 6KW lamp (the current ones from Christie) being the best bang for the buck on light...though I haven't seen any of the new LTI lamps that have their optimized arc-gaps.

The thing with Christie console is the heat. I would have in excess of 1000cfm per machine. Strong Ultra-80s will run cooler on the film and, possibly depending on projector, lens and shutter, more light. Kinoton's lamphouse will run the coolest and again, depending on the shutter/lens more light...however, you must be using pedestals to use it an the lamp table must be able to be adjusted to 1/8" lower than for a standard lamphouse.

As for lenses...depending on your throw, ISCO offers their red lenses (Ultra-Star PLUS) with a fast 1.7 version...under 100mm. A problem most drive-ins suffer from is that their focal lengths are very long due to throw. Once you get to 140mm...you start to loose light as your lens' speed is effectively slowed in the standard 70.6mm barrel diameter.

If you do have these super long lenses...I would seek out some old B&L Super-Cinefores in the 4" diameter barrels. They actually do a pretty decent job and will output more light on long focal lengths than modern lenses.

Good Luck.

Steve

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-15-2005 09:21 AM

Brad,
Don't forget that extra light you and I see and measure from the SLC is only apparent extra light according to Messrs Guttag and McLeod since the color temp on them is way off. also yout reds will appear black [Cool]

.

I have not experienced any extra amount of heat from the SLC, or the large Big Sky lamphouse who's mirror is very similar to the Christie than I have with the Strongs running the same size lamps. It would be quite easy to add a heat filter to the Christie if ever needed as is done in the Ultra 80. Were there alot of extra heat being generated in the SLC's I owuldn't be seeing triple the lamp life that I see from the Strongs.

At the Egyptian Theatre in Hollywood they changed from a pair of Kinoton lamphouses to a pair of the large Christies and got more light(apparently) and less focus flutter(definately).... hence less heat on the film.... Go figure that one out.

Mark

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Robert Throop
Master Film Handler

Posts: 412
From: Vernon, NY USA
Registered: Jun 99

posted 01-15-2005 09:27 AM

Monte:
The Futura series were carbon arc lamps. You must mean X60's?

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Tim Reed
Better Projection Pays

Posts: 5246
From: Northampton, PA
Registered: Sep 1999

posted 01-15-2005 10:05 AM

Kneisley had a Futura conversion kit.

A key to good drive-in screen illumination is you've got to get that stray light under control. Allow no general lighting a direct shot at your screen.

Douse or put shades over offending fixtures from both within the field and out. If lights from adjoining parking lots or businesses are creating the trouble, offer to put shades over them at your expense. If the business owner(s) balk, you have legal recourse. Yours is an existing business - long before the surrounding businesses moved in, and you can petition a judge to order the offending fixtures REMOVED entirely. Most businesses will agree at this point, since you are being nice enough to offer to do the work yourself and avoid putting the screws to them at the same time.

Also, 7KW is sales b.s. The area between the electrodes is larger than the reflectors can effectively use, so you end up with not much more light than you'd get with a normal 4KW lamp.

Try to keep your lenses at f/2.0 or under, and make sure the optical trains are perfectly aligned. Lamphouse alignment is critical -- particularly in a drive-in.

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Richard Greco
Phenomenal Film Handler

Posts: 1180
From: Plant City, FL
Registered: Nov 2003

posted 01-15-2005 10:56 AM

We have gates cooled with anti-freeze, it's been that way since before my manager started working there. Apparently, this 7k is a lot better than our existing 4k's and will be MUCH brighter onscreen. FWIW the house came shipped in a HUGE Sony Trinitron WEGA TV Box.

[ 05-08-2005, 04:59 AM: Message edited by: Richard Greco ]

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Ken Layton
Phenomenal Film Handler

Posts: 1452
From: Olympia, Wash. USA
Registered: Sep 1999

posted 01-15-2005 12:13 PM

Jack Ondracek is running the 7kw Big Sky lamphouses at the Rodeo 3 drivein. I've seen the results on screen and it's amazing! The picture he's got on that huge screen is brighter than many indoor houses!

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Tim Reed
Better Projection Pays

Posts: 5246
From: Northampton, PA
Registered: Sep 1999

posted 01-15-2005 12:35 PM

I wouldn't be surprised with Big Sky. Although, unless there's been a change in the optics since I've been out of the business, there wasn't that much of a difference in Strong's unit. Certainly not enough to justify the extra cost of the devices, the shorter life, or the extra power consumed.

Richard, good-quality lenses also have a great deal to do with light transmission and apparent brightness. Moreso than most owners will consider.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 01-15-2005 12:45 PM

quote:
Jack Ondracek is running the 7kw Big Sky lamphouses at the Rodeo 3 drivein. I've seen the results on screen and it's amazing! The picture he's got on that huge screen is brighter than many indoor houses!

Doesn't surprise me a bit Ken. We installed 8 of them at Thanksgiving Point and got results that were fantastic. The large Big Sky mirror os almost identical to the Christie mirror. One problem to be aware of is ignitor arc ofer to the blower by the negative lamp mounting support but Big Sky does have modification parts for that.

Mark @ CLACO

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Andrew McCrea
Jedi Master Film Handler

Posts: 645
From: Winnipeg, Manitoba, Canada
Registered: Nov 2000

posted 01-15-2005 05:41 PM

quote: Steve Guttag
As for lenses...depending on your throw, ISCO offers their red lenses (Ultra-Star PLUS) with a fast 1.7 version...under 100mm. A problem most drive-ins suffer from is that their focal lengths are very long due to throw. Once you get to 140mm...you start to loose light as your lens' speed is effectively slowed in the standard 70.6mm barrel diameter.

If you do have these super long lenses...I would seek out some old B&L Super-Cinefores in the 4" diameter barrels. They actually do a pretty decent job and will output more light on long focal lengths than modern lenses.

I've always found that the lens calculators tricky to use (I've fooled around with it a lot and have always had troubles)... Plus, I don't really know much about how lenses work... So, what do the mm do, and will they be larger for a bigger screen?

Thanks!

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99

posted 01-15-2005 05:46 PM

quote:
Don't forget that extra light you and I see and measure from the SLC is only apparent extra light according to Messrs Guttag and McLeod since the color temp on them is way off. also yout reds will appear black [Cool] .

Things must be different in Canada and up in Guttag-land then. My colors on the SLCs are excellent, and even if the extra light is "apparent", big friggin' deal. People don't watch movies with light meters. They use their eyes. The Christie SLCs have the best image I have seen from any lamphouse, ever.

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