How do cheap lcd projectors get more lumens than 16mm?

[slashmaster]

I'm trying to figure out why some of the cheap lcd projectors typically say they put out 1600, 1800 or 2000 lumens but the ELC lamp which is so common in quality 16mm projectors like Eiki or Elmo only puts out 900 or maybe 1100 if you get a multi mirrored bulb. How do the lcd projectors do it? Are lumens measured from the bulb or from the screen?

[bolextech]

LCD projectors typically use Metal Halide lamps which can output much more lumens per watt than a conventional quartz halogen bulb like the ELC bulb. I'm not sure how lumens are measured but I doubt it has anything to do with the screen. I would guess they take an incident light reading from the screen's position but aiming at the projector.

Cheers,
Jean-Louis

[slashmaster]

Thanks Bolextech! So Metal Halide is the answer. I just found this metal halide lamp meant for 16mm projectors http://www.lamptech.co.uk/Spec%20Sheets ... ARC350.htm it looks like the same shape as an ELC so I could put it in without having to mutilate anything. The voltage isn't the same though, it's 45 volts. Could using this bulb be as simple as finding 45 volts to power it?

[bolextech]

That's the old Marc 300 bulb available since the 1960s or 1970s I think. Many 16mm projectors were upgraded to this lamp. It takes a big-ass external power supply to run it however. The projector would typically sit on top on the power supply which weighed almost as much as the projector. The Marc 300 bulb would only last between 25 and 50 hours and it was recommended to keep it running as long as possible. Turning it off and reigniting too frequently would destroy it prematurely. Also when you would ignite it, the light was a deep purple color and it took about 45 seconds to reach its correct "white" color.
But, back then, it was in demand as it permitted for a much brighter picture without as much heat.

Afterwards came Xenon lamps which had much longer run times and didn't mind so much being turned off and on frequently. I'm sure nowadays there is even better technology available.

I think the main design problem was and still is how to efficiently focus these lamps into the narrow area of a 16mm frame size.

Cheers,
Jean-Louis

[slashmaster]

Thanks Bolextech! Are you saying that when people converted projectors to use the marc 300 bulb they could just buy a power supply meant to be put under the projector or they had to build one like that? Is it common for people to convert projectors to xenon or is that a lot more complicated?

[bolextech]

These Marc 300 conversions were often manufactured and marketed by the projector manufacturers themselves. Off the top of my head, I can think of Bell&Howell and Singer/Graflex models. I remember there was a company called Optical Radiation Corporation and I think they might have sold their own xenon conversions to popular 16mm projectors.

Working with Xenon lamps and power supplies is very dangerous and is not for the DIYer.

Cheers,
Jean-Louis

[bolextech]

Check out this link:

http://www.acofs.org.au/part_4_files/OC ... 0xenon.PDF

Cheers,
Jean-Louis

[slashmaster]

Thanks for finding that for me! It's very interesting.

[winbert]

When you are talking LCD projector, did you mean those projectors for data or showing movies?

Data projectors are indeed using high lumens for certain purposes.

But high-end LCD movie projectors are in fact using low lumens between 600-900 (some go to 1200).

Why we need high lumens if that is for home use. Don't your eyes will suffer when sitting for 2 hours more?

But I can understand that many people are easily to be sold by certain cheap things. That is similar to audio when dealers tend to boost the bass or set the treble high. This is just to show how "clear" the sound.

But audiophilists will keep everything flat. Because they are going to hear music for hours not just for "display only".

Same thing with LCD projectors, nowaday they tend to go high lumens, some are found to be 2200. And this trend is also being seen in the Digital Cinemas where many of them offfering high contrast/lumens and boom-bass sound making watching movies at the cinema is no longer enjoyable (at least for me)