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This topic comprises 6 pages: 1 2 3 4 5 6
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Author
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Topic: 7000 Watt Lamphouse for DI, good idea?
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Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!
Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999
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posted 01-15-2005 06:34 PM
quote: Andrew McCrea
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?
You probably aren't using them right. Use the Bell Theatre lens calculator, it is the easiest one by far, most don't need all the 'bells and whistles' for theatre design that the Schneider and ISCO programs have anyways.
Simply determine of you are going common height or commpn width, and input your throw distance and screen width/height (as applicable) and the type of film format you are calculating for, and voila! you get a pretty good idea what you will need, lens-wise. Just adjust the output of the lens calculator to the nearest shorter mm size and you have your lens in almost all cases.
As a rule, the larger the focal length in mm, the smaller the picture for a given screen size.
-Aaron
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Justin West
Master Film Handler
Posts: 271
From: Peoria, IL, USA
Registered: Jul 2001
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posted 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! ![[Smile]](smile.gif)
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 01-16-2005 09:30 PM
quote: Brad Miller
People don't watch movies with light meters. They use their eyes.
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 ![[Big Grin]](biggrin.gif)
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
3) Flat f2.0 170mm or 6 1/2"
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.
Steve
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![[Eek!]](eek.gif)
, 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.
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