HIGH INTENSITY DISCHARGE Bolex/Eumig sound projector lamp conversion

[Lee Mannering]

The first thing to say is all this is new to me although I have seen converted Elmo projectors using this modification to achieve greater screen illumination and a Elf 16mm projector. The light is good but the colour temperature from the HID lamp is different so the projected image will look somewhat different to a regular Halogen lamp which will probably trouble this Super 8 film maker a little always striving for perfection.

I believe the colour temperature of this HTI lamp to be around 6000K whereas a standard 12 volt 100 watt Halogen lamp is 3350K so that's going to be quite a different look on screen.

One HID lamp and one 240V on off push switch

I'm probably going to use a Bolex S8 sound projector as a suck it and see project, then if it works satisfactory alter one of my loved Eumig 807D machines.

Part 1. Order a HID 150 High Intensity Discharge lamp costing around £65, Ballast to drive it £58 Ventronic 150w and a mains on off switch 45p.

I think the first two problems to surmount will be making a dowser to block heat from the lamp damaging the film when not in motion and I'm guessing extra lamp cooling is going to be needed as well.

Watch this space!

[Maurice Leakey]

I must stress that the Xenpow HID 150 lamp cannot be switched on and off like a conventual lamp at the end of each reel change. It has to stay on for the duration of the show. Therefore, it needs a dowser to completely block the light during the change of spools.

But as Lee says, a more significant problem will be cooling. Most 8mm projectors seem to use a 100watt lamp. The HID emits 150watts of light and, of course, 150watts of heat. And as stated above, the lamp will stay on for possibly an hour or even more.

I suggest that anyone considering such a conversion should choose a 8mm projector with a 150 watt lamp, or even better, the 200watt of the Elmo GS-1200. This suggestion would probably negate the need for extra cooling.


Maurice

[Dominique De Bast]

It should probably be wise to use a projector that has a permanent fan in use or to modify the existing system to make it cooling without break.

[Lee Mannering]

I'm already formulating ideas for a switchable dowser in out to protect those valuable frames from frying, also a powerful fan which will be permanently on and although the humble Eumig does have permanent cooling it wont be enough for this job. Something along the lines of the HTI Beaulieu style fan would be ideal.
Lets not forget Eumig did actually modify a 810D to Xenon in prototype form 😍 You have to love a Eumig.

[John Armer]

Wouldn't it be great if we can get the sort of light output of HID lamps (or 200W / 250W halogens) from an LED? Perhaps it'll happen in the future. There shouldn't be any need for a cooling fan at all with LED.

[Maurice Leakey]

Here's the Eumig 850 :-

https://www.filmkorn.org/super8data/.../eumig_850.htm



Maurice

[Brian Fretwell]

Those Marc 300 power supplies weighed as much as the B&H 16mm projector fitted with it, I used one once and had to put it away after!!!

[Maurice Leakey]

There is a great advantage in using the Xenpow HID 150 lamp.
As its colour temperature is somewhat around that of the sun there is quite a lot of blue in it. This is a great assistance when showing faded prints on old Eastmancolor stock.


Maurice

[Lee Mannering]

Yes the Xenon 850 was a real projector and Dad and I got to see it at the Kent photo show. It was either 1976 or 77 bit foggy on date. Impressive to look at and the stand eumig had was something to behold, along with Noris and others. Memorable.
Oh and Fuji were also there promoting its film.

The LED lamp will eventually happen John it's already changed the way we film video in the trade along with stage and tv.

Project update: Ballast is up for delivery and I've a plan for a mechanical link to move dowser in and out.

[Steve Klare]

I believe a modern day film projector would be shutterless: a solid state pulsing power supply would turn the LED lamp on and off in sync with the film transport. It would flip from "two blade" to "three blade" automatically.

-just maybe we could have color compensation for red prints, but maybe in a world where we could buy a brand new machine now, we wouldn't be projecting red prints too.

[Maurice Leakey]

Steve
Were you aware that Philips pioneered a shutterless 35mm projector, the FP20, which actually had a pulsed lamp?

http://www.film-tech.com/ubb/f1/t005451.html

https://www.pearl-hifi.com/06_Lit_Ar...959_60-083.pdf


Maurice

[Steve Klare]

I'd never heard of that. I'd always imagined somewhere along the line somebody would have to try it with a strobe light, and the audience would walk away with headaches (-or worse...)

With an LED setup, it would be possible to have the intensity ramp up from dark and then ramp back down, just like a mechanical shutter.

[Nantawat Kittiwarakul]

"Flash/Strobe" LED as a light source would be really sensible. Its timing&duration could be easily controlled. So that would be possible to get 4-6 "flashes" per frame - totally flicker free projection.

Only gotcha is that how to squeeze that amount of light and pass it tru the tiny 8mm film frame? Unless that LED could be made relatively small (being close to single-point light source), overall light efficientcy wouldn't be that good.

[Steve Klare]

That's an up and coming technology: it's amazing what they've done with it in the last couple of years. So I'm sure they are working on squeezing the light down closer and closer to a point source. Even if they aren't doing it for we proud few, things like optical microscopes could use it.

I was at work a couple of years ago and I walked past a cart outside a lab they where were setting up a new microscope. There was a familiar little blue box on the cart, a projection lamp.(!) I picked it up and gave it a look: "EFR" (!!). (I was good: I put it back. I can get EFRs for 5-6 Bucks, new jobs aren't that easy!)

[Brian Fretwell]

Despite their efficiency I think the problem with high power small source LEDs is the heat dissipation, they don't really like high temperatures. Even if the LED size was small the heat sink on it would be large.
I've seen YouTube videos of high power LED torches people have made and the aluminium heat sinks have been the size you mainly see on high power amplifiers. Getting those to fit in the projector would be a problem.