Weird light levels

[Armand Daiguillon]

lightissue.jpg

Hey all,

I had two bulbs that were getting dim so we replaced them with brand new bulbs, but the light output is still really low on one of the projectors.
The projectors are Christie Solaria Ones with the christie cdxl-16 bulbs.
The solarias have a manual x y z adjustment for the bulbs, but no matter how much I adjust I cant get a reading on the projector for light output of more than 9500 on one of the projectors.
In contrast the other brand new bulb I installed in another projector is giving an output of 14,000

Anybody can think of anything else that can be done/adjusted to get a proper light output ?
Here are screen shots, the one labeled "Proj 1" is giving good output, the "Proj 2" has a brand new bulb - but less light output.
.
Volts and amps and watts to both seem close enough to not be an issue - the " ~fL " reading is the only discrepancy ....but I don't know what that means or if its relevant ?

Its frustrating !!! Most of my projectors are NEC 900C and those are so much easier - just screw in a new bulb and its done.


Any ideas ?

Thanks !!

[Marco Giustini]

You can't possibly wish your projectors were all NC900!

Intensity on a Christie is kind of a random value, it catches stray light along the light path. What matters is the light on screen. What you see on the UI in fL is what was set at installation/service. You really need to take a light reading on the screen to be sure.

The sensor is located behind a mirror, you can check your xenon mirror, the integrator rod and the fold mirror/mirrors. It goes without saying that you need to be qualified in order to service those parts and remember that the xenon bulbs you dislike are under high pressure even when cold and can explode any moment.

[Armand Daiguillon]

You can't possibly wish your projectors were all NC900!

Intensity on a Christie is kind of a random value, it catches stray light along the light path. What matters is the light on screen. What you see on the UI in fL is what was set at installation/service. You really need to take a light reading on the screen to be sure.

The sensor is located behind a mirror, you can check your xenon mirror, the integrator rod and the fold mirror/mirrors. It goes without saying that you need to be qualified in order to service those parts and remember that the xenon bulbs you dislike are under high pressure even when cold and can explode any moment.

The light reading on screen are low as well - one thing you said really caught my attention though, you mentioned the "~fL" listed on the interface is set at installation, so the fact that that is inconsistent between the projectors seems like it could be an issue ?
Is there a way to adjust ?

Thanks !

[Elia Orselli]

Those values are there for reference only: they don't affect projector behaviour. After lamp replacement and mechanical alignment, you have to measure light on screen and set lamp power according to that (if you still have headroom)

[Marco Giustini]

I'd ignore that number altogether. It also changes a lot while the light engine ages - the reading is taken before it.

You really need to measure the screen luminance before you can speculate further.

[Steve Guttag]

The fL number on a Christie S2 is near worthless. It is calibrated by the installer but measuring the lamp at 100% and at whatever the lower percentage value is for the lamp. It then interpolates from there. And, furthermore, it is just one setting. You can't have one for each lens zoom position. So, disregard the projector's fL number. At best it is a near-miss. At worst it is made-up.

FYI, when I install a Christie S2, I create different LiteLOC files for each lens zoom and label them for their format and measured light level. e.g "FLAT_14fL."

[Leo Enticknap]

If you don't have a light meter or photoradiometer with which to make an objective check, does the projector with the suspect reading subjectively look dimmer to you, comparing a white test pattern on both screens? If not, it's likely a sensor fault that can be ignored, as others above have suggested.

[Carsten Kurz]

You can buy a cheap luxmeter on ebay to at least compare projectors or after new bulb installations, or to optimise bulb allignment. That's still better than just judging screen brightness by eye.

[Leo Enticknap]

If you rely on one to optimize alignment, you'll likely end up with a nasty hot spot wherever the meter is aimed. The same applies if you use the alignment assistance tool on NEC S2 projectors. Its Barco equivalent is a little better, but if you rely solely on the numbers it gives you, you will still have a bit of a hot spot when you're done (especially on a curved screen). With a xenon lamphouse, I've always found that the initial ZYZ adjustment is best done by eye for uniformity, then check with a meter in several different places and make very slight touch ups after that if needed.

[Vern Dias]

You can also download a light meter app for your cell phone. I use one for my Google Pixel 6 Pro called .....wait for it..... Light Meter.

[Ryan Gallagher]

Speaking of metering, for just luminance... what is the best "pro" tool to use? Are there any affordable ones?

My impression was it would actually require a reflected light spot meter, and not a lux/ambient meter (but that can ballpark things if you can reach the needed area of the screen).

Obviously most pros probably use a full colorimeter that can also do luminance, but any luminance only suggestions?

[Leo Enticknap]

Harkness made one (which is about to be replaced by a new model, per their website). The last I knew its cost was nontrivial, but a lot less than a photoradiometer.

[Ryan Gallagher]

Harkness made one (which is about to be replaced by a new model, per their website). The last I knew its cost was nontrivial, but a lot less than a photoradiometer.

I actually have a couple of those, they pop up on ebay for cheap every now and then... probably need to be re-calibrated. They seem to be best for comparative values on multiple screens otherwise, and predominantly for digital if you take the approach of trying to fill the reticle guide lines with the illuminated screen.

For 35mm/70mm I want to meter the corners in more of a spot fashion, would the Harkness work in a pinch just by moving closer and taking a smaller average area reading?

EDIT: Probably not. Closer means brighter, and expect it is calibrated for full screen average type reading from idealized seating, perhaps center weighted. But I guess you could ignore the actual value and use it for relative corner metering. Not the full tool, but can do some of it. I expect to do corners "proper" you want to spot meter the corners sitting in those same idealized seats in the center of the room, not by moving down next to the screen to take your reading.

[Gordon McLeod]

I use the USL PSA as it transmitts the data from the seating area to the booth. The built in NEC and christie meter only serves as a method getting the peak light output not the distribution
Also I have had issues with the 2210 and Solaria 1 casing for the lamphouse module warping and producing very poor light

[Harold Hallikainen]

It's too bad the LSS-200 is no longer available. It provided luminance, chromaticity, and SPL measurement.

https://www.qsys.com/resource-files/...usermanual.pdf