8mm Forum: led lamps

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Topic: led lamps

Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted March 02, 2006 05:50 AM

Toshiba have produced a video projector with an 1500 ANSI Lumens LED Light sorce.
What is the viability of replacing the old halogen lamps in our 8MM projectors with this new superbright LED technology that is still developing? One of these type of new solid state light sorces has to be the way of the future and could it mean an affordable brighter light sorce for our projectors?

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Kevin Faulkner
Film God

Posts: 4071
From: Essex UK
Registered: Jun 2003

posted March 02, 2006 06:50 AM

Your spot on about this Mark, and its something I have also been watching. I think that the problem at the moment is concentrating the light on such a small area but your right I think that the technology is now virtually there and well worth watching. [Smile]

Kev.

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GS1200 Xenon with Elmo 1.0...great combo along with a 16-CL Xenon for that super bright white light.

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Tim Christian
Expert Film Handler

Posts: 219
From: Norfolk, UK
Registered: Jun 2003

posted March 02, 2006 01:03 PM

Concentration is just part of the problem. White LEDs are limited to around 10 W at the moment. Techniques have been developed for adding and concentrating the beams of several LEDs into one light pipe that illuminates the screen. However, these require special prisms.

It is expected that LED car headlamps will appear this year, and they may contain optics that would help as well as combinations of LEDs requiring 12 V supply.

At present, LEDs are no more efficient than HID lamps so there is still a lot of heat to get rid of. Practical choices remain halogen up to about 200 W then HID/short arc lamps for higher powers.

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Tim

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Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted March 06, 2006 06:01 AM

On the subject of concentration of light, my Eumis Mark S standard 8 projector takes a 100w capsule Lamp with a separate reflector behind it and interestingly what appears to be a lense arrangement in front to focus the light on to the 8mm gate.
I have not seen this on any other projector before.

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Tim Christian
Expert Film Handler

Posts: 219
From: Norfolk, UK
Registered: Jun 2003

posted March 06, 2006 07:14 AM

It is a common arrangement in larger-format projectors and slide projectors. Before the advent of lamps with integral reflectors, and the elliptical-reflector lamps used today, it was a common arrangement in R8 projectors, too.

With regard to LEDs, since the output of a number, maybe ten, LEDs would be needed for a S8 projector, it would be possible to use separate blu, green and red LEDs combined to produce white light. This would enable colour temperature to be adjusted. Interesting?

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Tim

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Tony Milman
Phenomenal Film Handler

Posts: 1336
From: United Kingdom
Registered: Jun 2003

posted March 06, 2006 12:38 PM

A friend of mine sells LED torches. I wonder if his German company that supplies them would have anything suitable. I might need some help with specification though

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Tony

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Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted March 06, 2006 01:59 PM

Yes Tim, very interesting being able to adjust the colour temperature with different lED's.
In a comparison with my 100w Elmo vs my 100w Eumig, the Eumig gives a white/blueish light while the Elmo { with a faster 1.1 lense} gives a very, very yellow light. I prefure the colour temperature of the Eumig. I will have to do some tests with a light meter to see how they compare on brightness.
I wonder if the Eumig is loosing light due to the design of extra optics in front of the lamp over the reflector lamp of later projectors.

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Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted March 08, 2006 12:18 PM

As I suspected, the Reflector lamp was reading considerably brighter in my light meter test.
The optical focusing arrangement on these older R8 projectors could be perhaps be one answer to focusing a cluster of LED's.

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Mark Norton
Master Film Handler

Posts: 330
From: Hampton Hill, Middlesex, U.K.
Registered: Feb 2004

posted March 12, 2006 06:24 AM

Whilst on this subject, saw a outrageously bright lupine bycycle lamp. Looked very similar to a 8mm reflector lamp but as the owner informed me this has a Xenon HID Halide lamp in the middle and 20 superbright LED's fitted arround the inside edge of the reflector. Runs off of a battery the size of a water bottle for around two hours. , but they are £300 and up, replacement Xenon HID Bulbs being around £130.
Could easily fit most projectors, now there's a thought.

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