This is topic 7000 Watt Lamphouse for DI, good idea? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.


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Posted by Richard Greco (Member # 2032) on 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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Posted by Brad Miller (Member # 2) on 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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Posted by Richard Greco (Member # 2032) on 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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Posted by Monte L Fullmer (Member # 2797) on 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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Posted by Stephen Jones (Member # 16) on 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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Posted by Steve Guttag (Member # 268) on 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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Posted by Mark Gulbrandsen (Member # 72) on 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 .

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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Posted by Robert Throop (Member # 61) on 01-15-2005, 09:27 AM:
 
Monte:
The Futura series were carbon arc lamps. You must mean X60's?
 

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Posted by Tim Reed (Member # 137) on 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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Posted by Richard Greco (Member # 2032) on 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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Posted by Ken Layton (Member # 133) on 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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Posted by Tim Reed (Member # 137) on 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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Posted by Mark Gulbrandsen (Member # 72) on 01-15-2005, 12:45 PM:
 

quote:

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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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quote: Steve Guttag

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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.

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quote:

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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] .

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quote: Andrew McCrea

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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?

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quote: Brad Miller

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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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Brad I am in 100% agreeance with you. Christie consoles are the best light source on the planet for a theatre. I would rate the Big Sky stuff as #2.

Mark
 

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Posted by Scott Norwood (Member # 30) on 01-15-2005, 10:24 PM:
 
The Christie lamphouses give good light output, but is there any reason why they need to be so freaking huge? They just look ugly and out of scale with everything else when compared to Strong or Cinemeccanica or any other brand of lamphouse. Not that the customers care about any of this, of course, but it annoys me.

For 3k or 4k, I really like the light output of the Cinemeccanica ZX-4000H lamphouses, though changing a bulb in those requires more disassembly than should really be necessary (the entire top of the lamphouse need to be removed).

One of the best on-screen images that I've seen came from an old JJ with water-cooled gate and a ZX-4000H lamphouse with 3kw bulb, projecting onto a 33-foot indoor screen. The picture was rock-steady and the illumination was perfectly even, edge to edge, corner to corner.
 

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Posted by Brad Miller (Member # 2) on 01-15-2005, 11:18 PM:
 
I would have to rate the lamphouses I have worked with or seen in this order:
1 - Christie SLC
2 - Kinoton
3 - Cinemeccanica Zenith (we had these at Northpark)
4 - Xetron/Neumade (current model)
5 - Cinemeccanica (whatever their generic consoles are)
***noticeable jump down in quality***
5 - Strong Super Lume X (would be great if not for that damned hot spot)
6 - Strong (other models - hot spot city)
7 - older model Christie lamphouses (70s vintage)
8 - ORC (any model)
9 - CFS (The worst of the worst! In fact, how can these suck so bad??? )

The Kinoton lamphouses could be #1, but I need to get my hands in there to make sure the units I'm basing this on were truly aligned properly. Given their price, Christie SLC still wins.

I will visit the Cinemark in Denton once they open and report back on MiT lamphouses. I have no reason to believe Bevan and company won't be in there personally tweeking everything to make sure they get future Cinemark sales, so it should be an ideal theater to judge their performace by.
 

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Posted by Justin West (Member # 920) on 01-15-2005, 11:41 PM:
 
Hey, Richard, I recall the big "shade" that was next to that screen...it was almost like a 2nd screen was built beside the main screen but I could tell it was to block out the ambient light from the nearby commercial strip (where your drive-in is situated). Too bad they tore it down! BTW, this seems like a perfect topic to bring this up: I am in search of lenses for a drive-in...what are some good sources you operators and techies could recommend for some long throw drive-in lenses of the following measurements? I did use the Schneider optics calculator and Tim Reed helped me on the conversions:

1) Scope: 4 1/2" backup with reverse anamorphic attachment (9" with normal scope)
or f2.0, 115mm backup

2) Scope: 5" backup with reverse anamorphic attachment (10" with normal scope)
or f2.0, 125mm backup

3) Flat f2.0 170mm or 6 1/2"

4) Flat f2.3 150mm or 5 3/4"

I plan to use lenses 2 and 3 on an XL and 1 and 4 on a Century C. Yes, I am scavenging but I am just trying to get things up and running. I am learning a lot about the booth, that is for sure, but I know I've got a long way to go!
 

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Posted by Gordon McLeod (Member # 33) on 01-16-2005, 10:03 AM:
 
I rated them as follows
Ernemann
Kinoton
Cinemecanica current version
Strong Super lumex/super80
XenexII
 

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Posted by Mark Gulbrandsen (Member # 72) on 01-16-2005, 10:24 AM:
 

quote: Brad Miller

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The Kinoton lamphouses could be #1, but I need to get my hands in there to make sure the units I'm basing this on were truly aligned properly. Given their price, Christie SLC still wins.

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quote: Brad Miller

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9 - CFS (The worst of the worst! In fact, how can these suck so bad??? )

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You bet ya they are the worst , even the ORC 1000 is better than this pile of metal and glass. We are working up a conversion to install the Christie plenum kit in these since there are so many in this neck of the woods. The rectifiers are actually pretty good though and were supplied by LP Associates.

quote: Brad Miller

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I will visit the Cinemark in Denton once they open and report back on MiT lamphouses. I have no reason to believe Bevan and company won't be in there personally tweeking everything to make sure they get future Cinemark sales, so it should be an ideal theater to judge their performace by.

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quote: Man Up North

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XenexII

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quote: Brad Miller

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People don't watch movies with light meters. They use their eyes.

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Shirly you jest...your patrons don't come in with their chromaticity meters? Christ, I'm always having to run white light for them between the ads and the feature to check calibration

No you are right on that one...but I do have studio screenings with DPs that will nail a theatre for having reflectors too blue....always happens in a Christie thatre. Note, Kinoton lamphouses have color temps near 6000K. Christie is bluer than that. Strong typically lands anywhere in the 5000s but most are in SMPTE's range of 5400K +600/-200K.

My most recent encounter with a Christie SLC was a top to bottom realignment with a new reflector that while yielded a massive improvement, did not obtain the light levels I would obtain using Strong/Simplex equipment on the same size screen. Again, this was a Studio screening so there were many eyes and meters on the screen that were in the know. This was a Christie/Christie installation. We did two theatres, one projector had a single bladed shutter, the other was a 2-wing shutter. The single blade one won by about 8% and the apparant flicker was less on the single blade...so any Christie users out there I would say the single blade shutter was a real improvement (as would be predicted).

As to heat...I have done the same test on Christie SLCs running 6KW and Ultra-80s running 6KW (both were Christie lamps, natch) and the results show the film takes less heat from the Strong. The test was simple, if you have Schneider's test film (CLT-2000)...On both systems, a 10-foot loop was threaded and run for 10-minutes continiously...the Christie showed definate signs of embossing (though still runnable and not apparant from downstairs) where as the Strong was just barely starting to show signs of embossing). Both Christie and Strong had heat filters installed.

Kinoton, on the other hand, has the least heat of them all. We've run 5KW on 16mm without any problems what so ever. Light out of a Kinoton tends to be more uniform than from the metal reflector offerings but not necessarily more plentiful.

What lenses one uses will no doubt play into the light output...how the reflector directs the light into the inlet pupil of the lens. ISCO's red lenses work EXREMELY well with Strong's relectors and tend to pass more light than Scheniders, all other things being equal (this is in the under 100mm range...above 100mm they seem identical). I do not believe this will necessarily be the case with all relector lens combinations though.

In the DLP department...I've worked with Barco's DP50s quite a bit at the AFI/Silver and have had some experience with the Christie DCP line of projectors...the Christie seems to run cooler and have more light than the Barco offering with the same size lamp. Note, the Barco uses the Kinton SK-50 console so again...the lamphouse does not tell the whole story in the light equation...all things must work together.

I will say the Christie SLC (and their Phoenix kits for older CH series consols) are significantly better than their K and previous lamphouss by a wide margin.

I don't think the SLC is bad at all but I do think they need to get their reflectors color temps within SMPTE spec and get their heat down. They are a good console/lamphouse I do prefer the Super Lume-X and Ultra-80 though.

quote: Justin West

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3) Flat f2.0 170mm or 6 1/2"

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quote:

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3) Flat f2.0 170mm or 6 1/2"
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How does that work, the theoretical fastest a 170mm lens could be in a 70.6mm lens barrel is about f/2.5 unless you have a 4-inch (101.6 mm) diameter lens.

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Oops, it should have been f2.4 170mm

Thanks! BTW, can you recommend any source of good used lenses of this size?
 

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Posted by Tim Reed (Member # 137) on 01-16-2005, 10:31 PM:
 

quote: Steve Guttag

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How does that work, the theoretical fastest a 170mm lens could be in a 70.6mm lens barrel is about f/2.5

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quote: Steve Guttag

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The Super-Cinefor that I listed will be brighter than the new Schneider and probably just as sharp.

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Although today's "state-of-the-art" lens designs do have better sharpness across the image, the most notable improvement was in the contrast of the image. For a drive-in, the older designs are very serviceable, and may offer a slight light advantage as noted by Steve, especially for the very long focal lengths.
 

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Posted by Gordon McLeod (Member # 33) on 01-17-2005, 08:32 PM:
 
If memory serves didn't kollmorgen or Hilux used to make a extremely fast long focal length lens in the 4" diameter that was f 1.7
 

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Posted by Mark Gulbrandsen (Member # 72) on 01-17-2005, 10:05 PM:
 
Yes, we have boxes of 4" diameter Kollmorgen and B&L's in the CLACO "Retired Equipment Dungeon". And there are definately 4 inchers in there.

Our last In Town Drive In uses a special 9.5" Kollmorgen for its flat aspect ratio.

Mark @ CLACO
 

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Posted by Justin West (Member # 920) on 01-17-2005, 11:06 PM:
 
Hmmm, well that Super-Cinefor sounds interesting...but the lens opening on the Century C I have is smaller than 4" diam. Is there an adapter to accomodate this model lens and, if so, is it advisable to use?
 

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Posted by Tim Reed (Member # 137) on 01-18-2005, 01:57 AM:
 

quote: Steve Guttag

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knowing the physics of the lens should help in choosing the most suitable one.

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That, and knowing what's available. But it doesn't entail splitting hairs over the manufacturer's rating. C'mon, now. You can only go by what's on the barrel.

If 4" B&L's are available, and if they have not yellowed as their red-ringed (and now, some silver-ringed) anamorphic mates have, then that certainly would be a good choice under the circumstances -- although I have not seen any of those around for several years, at least not in good condition. But good suggestions for sources. Thanks all.

That's right, Gordon, I believe it was Kollmorgen.
 

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Posted by Steve Guttag (Member # 268) on 01-18-2005, 10:34 AM:
 

quote: Tim Reed

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That, and knowing what's available. But it doesn't entail splitting hairs over the manufacturer's rating. C'mon, now. You can only go by what's on the barrel.

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quote: Steve Guttag

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Manufacturer's tend to stretch the truth in their ratings and to just go by what is on the barrel will yield you, in the case of lenses, wrong focal lengths

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quote: Steve Guttag

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Justin...if you have a small lens mount "C" then the Schneider 170mm is your best bet.

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quote: Steve Guttag

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when considering light, the "f" number is important.

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No kidding, Sherlock. You're not telling me anything I haven't known since you were in high school. Obviously, you want the fastest you can get for a drive-in, but if they ain't got a fast one, heh-heh... they ain't got it! Saying, "Oh, it's really more like f/2.4" might make you feel smart, but it changes nothing.

quote: Steve Guttag

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it would be better to recognize that the physics of optics is suggesting that either the lens is not 170mm or it is not indeed f/2.4.

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quote: Steve Guttag

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You are welcomed to ignore me too.

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quote: Tim Reed

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Nothing can prevent you from getting a lens that has the wrong focal length on the barrel! That's the manufacturer's problem, not yours. This has no bearing whatsoever on making recommendations for a lens compliment.

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quote: Tim Reed

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Ummm...he had that info already. Obsessing over a tenth of an f-stop didn't change things one iota.

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quote: Tim Reed

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No kidding, Sherlock. You're not telling me anything I haven't known since you were in high school.

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quote: Tim Reed

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Obviously, you want the fastest you can get for a drive-in, but if they ain't got a fast one, heh-heh... they ain't got it! Saying, "Oh, it's really more like f/2.4" might make you feel smart, but it changes nothing.

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quote: Tim Reed

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Why? No one's designing lenses here, so it doesn't matter.

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quote: Tim Reed

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Most of us know a particular len's "mileage may vary" from what's stamped

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quote: Tim Reed

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You take yourself too seriously.

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quote: Richard Greco

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ya'll lost me as soon as you started with the "f" numbers

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quote: Tim Reed

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Most of us know a particular len's "mileage may vary" from what's stamped

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quote: Steve Guttag

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when considering light, the "f" number is important.

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quote: Justin West

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1) Scope: 4 1/2" backup with reverse anamorphic attachment (9" with normal scope)
or f2.0, 115mm backup

2) Scope: 5" backup with reverse anamorphic attachment (10" with normal scope)
or f2.0, 125mm backup

3) Flat f2.0 170mm or 6 1/2"

4) Flat f2.3 150mm or 5 3/4"

I plan to use lenses 2 and 3 on an XL and 1 and 4 on a Century C

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Lens 3 was to be used on a Simplex XL...I therefore stand with going with an older 4" diameter lens, like the Super Cinefor, it will be brighter without any real image quality penalty.

Steve
 

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Posted by Mark Gulbrandsen (Member # 72) on 01-23-2005, 10:46 AM:
 
I agree Steve. He will get a bit lower contrast ratio with that 4" lens but in a drive in situation that may be an advantage and give more apparent brightness which in that situation is a good idea. And yes the 4" will in theory give more light overall just because of its geometric size assuming the glass and coatings are at least close to todays stuff. The downside with the 4 inchers are the cememted element groups.

Mark
 

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Posted by Justin West (Member # 920) on 01-23-2005, 02:36 PM:
 
While I am still new to the concept of f-stop and proper lenses, I appreciate the theoretical vs. street-wise discussion going on...as well as the advice, from all. I have started looking at some old 4" lenses...Kollmorgens, as a matter of fact, but of the two that had potential for my needs, one had a star-shaped burnmark about 3/4 of the radius from the center and the other one had tons of bubble or water droplets situated as if between layers of the lens(es).

Mark: would you elaborate a little on this "cementing" issue with such lenses? Thanks agin!
 

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Posted by Mark Gulbrandsen (Member # 72) on 01-23-2005, 02:44 PM:
 
Justin,
The cement used in those older lenses was basically a highly pure derivitave made from balsam sap. Its just called Balsam by potical techs and is easily burned in those older lenses with high temperatures that large arcs and xenons can put out. Ususally its the rear group or the second group in from the rear that this happens to. That star you mentioned is actually the Balsam crazing from heat and stress, its melted and the elements have pulled apart due to heat expansion and stress!

Not to worry though as we can have those cement problems repaired and today the elements are re-cemented with more modern U-V cured adhesives that will not be affected by heat. These newer adhesives are also much more optically transparent than the Balsam that was used back then. Even anamorphics with burned cement or crazed elements can be repaired! We are fortunate to have access to a local retired Air Force optical tech that does this sort of work today for a living and he does all of our older lens repairs. I have re-cemented lenses myself while at Canon USA but CLACO does not have a "Clean Room" atmosphere to allow us to do it in house.
Mark @ CLACO
 

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Posted by Richard Greco (Member # 2032) on 01-23-2005, 06:51 PM:
 
Hey Justin, FYI

There is a 4th screen going up at my DI, sigh..... There are many things I have to say about that, but getting rid of a 55 year old marquee really stinks in my humble opinion.
 

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Posted by Richard Greco (Member # 2032) on 01-24-2005, 11:08 PM:
 
Ok, I just read on one of my new flat lenses, "F 1.9" What does this number mean?
 

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Posted by John Pytlak (Member # 331) on 01-25-2005, 11:00 AM:
 
It's the aperture or f-number. Essentially it is calculated by dividing the focal length of the lens by the effective diameter of the aperture. For example, if you have a 100mm focal length lens and an effective aperture diameter of 50mm, you have an f/2.0 lens. If you reduce the effective aperture diameter to 25mm, the lens is f/4.0.

The lower the f-number (larger the aperture diameter), the more light the lens can transmit, and the less "depth of focus" the lens has.
 

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Posted by Justin West (Member # 920) on 01-25-2005, 11:56 PM:
 

quote: Richard Greco

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Hey Justin, FYI

There is a 4th screen going up at my DI, sigh..... There are many things I have to say about that, but getting rid of a 55 year old marquee really stinks in my humble opinion.

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Awww, that is a disappointment...it's a nice marquee, nothing extravagant but a nice neon marquee...they're not going to tear it down are they Richard? Surely they would disassemble it from the structure, for re-use down the road or repositioning elsewhere??? I hope it would not be replaced by some plastic faced sign with fluorescent tubes behind...UGH!

BTW, Mark: Thanks for the cementing lenses info...could you advise on the lens that had tiny bubbles or water droplets sandwiched within? Is a lens in this condition usable? What possibly led to this condition? thanks.
 

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Posted by Mark Gulbrandsen (Member # 72) on 01-26-2005, 12:04 AM:
 

quote: Justin West

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BTW, Mark: Thanks for the cementing lenses info...could you advise on the lens that had tiny bubbles or water droplets sandwiched within? Is a lens in this condition usable? What possibly led to this condition? thanks.

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quote: Steve Guttag

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I don't tend to guess at the outcome of a projection systems I set up.

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quote: Laurence Hammett

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When you look at these screens it is like going to a walk-in.

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What is this... some sort of Joke? FYI, Walk-ins typically run at 16 foot lamberts or a tad more...... Your 5.5 foot lamberts is just a tad bit shy of that 16fl mark SIR..... Also don't forget to let everyone know about the incredibly SHORT lamp life, and good luck getting that early failed Osram credited under warranty! Also, which Xenex's are they and what projectors?



Mark @ CLACO
 

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Posted by Laurence Hammett (Member # 1134) on 02-09-2005, 09:36 PM:
 
If you were to get 16fl in a drive-in it would be washed out and you would see the slats in the screen. I will leave it to other more brilliant people in this forum to explain why just looking at fl is a mistake. It has something to do with light per square foot of screen area. The bigger the screen the less total footlamberts necessary to achieve optimum light. Also the definition is different because of the increased photons hitting the screen.
I didn't pay attention to what model Zenex's. The projectors are standard simplex xl's
 

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Posted by Mark Gulbrandsen (Member # 72) on 02-09-2005, 09:42 PM:
 
You've been brainwashed by someone(north of the border) thats for sure! I left a customer in North Central Indiana with close to 14 fl on his 50 foot D.I. screens several years ago(running just 3kw). The images were terriffic! No visible slats either.... a well maintained screen also makes a huge difference...

Mark @ CLACO
 

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Posted by Richard Fowler (Member # 893) on 02-10-2005, 09:01 AM:
 
The Kneisley Xenex I lamphouse uses a glass reflector and still is made as a production item. The existing reflector does work great for medium and long throw situations based of the F- speed of their reflector. The man in Canada has several "custom" reflectors? I could see the expense of having one glass blank mold made but several? He may have one and speced the balance from the glass reflector companies in Europe and Asia. 16 foot lamberts will wash out most prints are timed for 12 - 16 and it is indeed rare that timed thin prints for drive-ins are readily available. The large image being acceptable at a lower light output if this image surrounds your field of view, such as IMAX but in a drive in situation...outside of the first row, your eyeballs will not be overwhelmed.
 

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Posted by John Pytlak (Member # 331) on 02-10-2005, 02:31 PM:
 
SMPTE Recommended Practice RP12, "Screen Luminance for Drive-In Theaters" specifies:

quote:

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4 Luminance level
4.1 In an ideal situation, when permitted by the
technology of motion-picture projection, and when
the viewing environment is sufficiently close to
that of the indoor theater, the screen luminance
and distribution shall be that specified in
ANSI/SMPTE 196M, 16 fL ± 2 fL (55 cd/m2 ± 7
cd/m2), as measured from a position on the
longitudinal centerline of the ramp area and midway
between the foremost and rearmost ramps.
4.2 The recommended minimum luminance at
the center of the screen shall be 7 fL (24 cd/m2),
as measured from the central position defined in
4.1.
4.3 When maximum compromise must be made,
as discussed in annexes A.1 and A.2, the luminance
at the center of the screen, measured
from any car position, shall in no case be less
than 4.5 fL (15 cd/m2).

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quote: Laurence Hammett

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I am no fan of osram either but Osram didn't design this bulb for one and Robert says he hasn't had a bulb explode and if it did the bulb maker pays for it under warranty.

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quote: Laurence Hammett

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500% beats 30% any day

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quote: Laurence Hammett

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As to hi-speed movements it is an extra expense and I can't see anyone getting a spare if they are that scarce. If you have to put in a standard one you have to replace the shutter or risk Ghosting.

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quote: Laurence Hammett

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Robert actually started out with metal but found that they loose light quickly as they degrade which is untrue of most glass.

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quote: Laurence Hammett

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We have had one house up for over 6 months with no degrade but in the same venue I replaced the Christie reflectors with good ones and within 6 months the centers had severely degraded Using the short arc LTIs. This isn't the bulb's fault.

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No, it was probably your exhaust systems fault. INadaquate air flow is the largest cause of premature reflector and lamp failure.

It seems to me that at 5.5 fl you have quite a ways to go. You may also need HS movements a better maintained screen and or new electronic projectors..... And thats 5.5fl with a new lamp....remember, xenon lamps have a decline in output after the first quarter life. That would resonably put you back around 4.7 fl.

Mark @ CLACO
 

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Posted by John Pytlak (Member # 331) on 02-11-2005, 11:05 AM:
 
Perforation wear was one disadvantage of the high speed (5:1) intermittents. With durable modern polyester (Kodak ESTAR) base print film, this is no longer an issue.
 

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Posted by John Hawkinson (Member # 1135) on 02-11-2005, 01:39 PM:
 
Is it possible there is some sort of measurement error going on here? 5.5 fL is pretty dim. But some meters can measure in candela/meter^2 as well. If you have the meter set wrong and misread the decimal point, 55 candela/meter^2 is 16 fL, which is entirely reasonable.

12-16fL is definitely not outdated. It is the standard for Xenon lamps in indoor theatres, and if you go below that, it definitely produces an undesirable image.

--jhawk
 

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Posted by Laurence Hammett (Member # 1134) on 02-11-2005, 01:47 PM:
 
The Longer the throw the bigger the picture the less foot lamberts. Look at my earlier post for one of the screens stats. Just looking at footlamberts is a generality. You must take into account the above.

You are not going to get 16 footlamberts aiming at the moon! See what i am getting at.

If you have a smaller screen and shorter throw you will get more light (per square foot). More footlamberts. isn't that obvious?

A lamphouse will put out only so much light. Put the screen closer and smaller and the light is reading more footlamberts. Make the screen bigger and farther away and it reads less foot lamberts.

HOWEVER

ALL the light hits the screen. So 5 or more times the light is still 5 or more times the light.
 

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Posted by John Hawkinson (Member # 1135) on 02-11-2005, 01:52 PM:
 
Actually, the throw has nothing to do with luminance, for any reasonable distance (ignoring atmospheric issues, which can come
up for DI). It's merely a function of the light output and the size of the projected image.

--jhawk
 

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Posted by Richard Fowler (Member # 893) on 02-11-2005, 02:04 PM:
 
Physics 101
 

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Posted by Mike Babb (Member # 1379) on 02-11-2005, 03:59 PM:
 
Almost every Technalight install we've been involved with is using Osram 2K W/H and 3K W/H bulbs, basically the same as the theatres had been using before but in many cases we lowered the bulb size for a house. In all cases we increased light.

I'm not aware of any bulb life issues and also am not aware of any differences in reflectors targeted to specific houses. There are two that I've seen, both the same size and shape, one had an extra reflective coating.

You do have to deal with certain cooling issues depending on the lamphouse.

I am not here to sell Robert's product but I will say you should talk to him and check out an install if possible including light readings before and after before dismissing him.
 

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Posted by Chris Hipp (Member # 1788) on 02-11-2005, 06:09 PM:
 

quote: Laurence Hammett

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If you have a smaller screen and shorter throw you will get more light (per square foot). More footlamberts. isn't that obvious?

A lamphouse will put out only so much light. Put the screen closer and smaller and the light is reading more footlamberts. Make the screen bigger and farther away and it reads less foot lamberts.

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quote: Mike Babb

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Almost every Technalight install we've been involved with is using Osram 2K W/H and 3K W/H bulbs, basically the same as the theatres had been using before but in many cases we lowered the bulb size for a house. In all cases we increased light.

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